Re: [time-nuts] RS 232
Since there is repeated request for the circuit se attachment. My question
is what can be done to get a positive voltage from some of the other unused
pins of the DB 9 connector. What is needed is any where from 3 to 15 volt.
Diodes work with 1 mA but I set Rx for 2 mA. Any thing else look at H11
data sheet.
Bert Kehren
In a message dated 7/26/2013 4:06:37 A.M. Eastern Daylight Time,
rexa@sonic.net writes:
FWIW, it was clear as mud for me too.
Bert began with, "Since joining time nuts over four years ago I have
not used a single MAX
232 chip. Two reasons MAX do not give me isolation and do generate noise
in critical applications."
From that I took that he was doing RS232 using opto isolators. That
implies + and - voltages to me. Where do they come from and where are
they relative to the isolation boundary? If the goal is really
isolation, how do these supplies get isolated? If the noise is cured by
isolation, these details seem important as the supplies need isolation
too. Maybe the switcher in the MAX232 is causing the noise. Then how do
we get a negative supply from, say, +5V without the noise? Then, maybe
he was saying RS232 sucks and this other way (not RS232 compatible)
works better.
The word picture of Bert's solution, which provided more details, left
me less much less than clear too. Maybe I'm just not up on circuit
shorthand terminology enough to follow what sort of current limiter is
limiting what current to what, and what is being blocked by a diode from
which negative level. Not really sure if I even got the big picture of
what he is describing. Is it an isolated equivalent of a MAX232
interface or something else that wouldn't talk to an RS232 device?
So, more clarification, or possibly that picture (~= 1k words) might
help. Or maybe I'm just obtuse and everyone else is getting it. (Seems
Marki may also be in the confused camp.)
On 7/25/2013 3:34 PM, Mark C. Stephens wrote:
Although your description,
" I prefer the use of two H11 opto couplers which
work perfect. On the receiving end the diode along with a current
limiter
and blocking diode for the negative level works perfect. On the output
side
a power source is needed." Is a perfect circuit description, I'd be
more confident with a schematic :)
--marki
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of EWKehren@aol.com
Sent: Friday, 26 July 2013 5:32 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] RS 232
I do not understand your question, I am referring to low noise
applications like counters for dual mixers or other AV measurements, but also Shera
and even Tbolt where external noise should be kept to a minimum. When you
chase 1 E-14, isolation is key and I always like to err on the cautious
side and as I stated we use blue tooth or USB but in the case of USB there
are always H11 in the circuit. Some still like to use RS 232 and the
subject came up and I have on my boards H11's like on the counter Corby uses
but he ended up using an external power source and I like to eliminate that
requirement. David had the right answer using the power that the RS 232
mouse uses out of a DB 9, started looking but I do not have one any more
and I can not find any data.
Bert
In a message dated 7/25/2013 2:48:43 P.M. Eastern Daylight Time,
marks@non-stop.com.au writes:
Hi Bert,
I am sure your circuit is clear in your head, but would you mind
attaching detail?
You have perked my interest with the "low-noise" keyword ;)
-marki
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of EWKehren@aol.com
Sent: Thursday, 25 July 2013 11:39 PM
To: time-nuts@febo.com
Subject: [time-nuts] RS 232
Since joining time nuts over four years ago I have not used a single
MAX
232 chip. Two reasons MAX do not give me isolation and do generate
noise
in critical applications. I prefer the use of two H11 opto couplers
which
work perfect. On the receiving end the diode along with a current
limiter
and blocking diode for the negative level works perfect. On the output
side
a power source is needed. If one uses an USB adapter it does have the
- 5
volt which again works perfect. How ever many prefer to use RS 232
direct and that is why I hope to get some comments and suggestions from
the
list. Corby used on our counter circuit that he described a separate
power
source.
Present MAX circuits use a + 1.4 volt threshold but considering legacy
the question is what should the voltage swing be to make it compatible
for
most PC's and what options exist to get the necessary voltage. In the
past
other pins on the RS 232 port where an ideal power source. Still an
option?
Bert Kehren
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Any of the PC (native serial or USB/serial adapter) modem control lines can be used to get a positive or negative voltage. In your case look at pin 7.
See comments at the end of http://leapsecond.com/tools/comtick.c
/tvb
Sent from my iPad/mini
On Jul 26, 2013, at 4:01 AM, EWKehren@aol.com wrote:
Since there is repeated request for the circuit se attachment. My question
is what can be done to get a positive voltage from some of the other unused
pins of the DB 9 connector. What is needed is any where from 3 to 15 volt.
Diodes work with 1 mA but I set Rx for 2 mA. Any thing else look at H11
data sheet.
Bert Kehren
In a message dated 7/26/2013 4:06:37 A.M. Eastern Daylight Time,
rexa@sonic.net writes:
FWIW, it was clear as mud for me too.
Bert began with, "Since joining time nuts over four years ago I have
not used a single MAX
232 chip. Two reasons MAX do not give me isolation and do generate noise
in critical applications."
From that I took that he was doing RS232 using opto isolators. That
implies + and - voltages to me. Where do they come from and where are
they relative to the isolation boundary? If the goal is really
isolation, how do these supplies get isolated? If the noise is cured by
isolation, these details seem important as the supplies need isolation
too. Maybe the switcher in the MAX232 is causing the noise. Then how do
we get a negative supply from, say, +5V without the noise? Then, maybe
he was saying RS232 sucks and this other way (not RS232 compatible)
works better.
The word picture of Bert's solution, which provided more details, left
me less much less than clear too. Maybe I'm just not up on circuit
shorthand terminology enough to follow what sort of current limiter is
limiting what current to what, and what is being blocked by a diode from
which negative level. Not really sure if I even got the big picture of
what he is describing. Is it an isolated equivalent of a MAX232
interface or something else that wouldn't talk to an RS232 device?
So, more clarification, or possibly that picture (~= 1k words) might
help. Or maybe I'm just obtuse and everyone else is getting it. (Seems
Marki may also be in the confused camp.)
On 7/25/2013 3:34 PM, Mark C. Stephens wrote:
Although your description,
" I prefer the use of two H11 opto couplers which
work perfect. On the receiving end the diode along with a current
limiter
and blocking diode for the negative level works perfect. On the output
side
a power source is needed." Is a perfect circuit description, I'd be
more confident with a schematic :)
--marki
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of EWKehren@aol.com
Sent: Friday, 26 July 2013 5:32 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] RS 232
I do not understand your question, I am referring to low noise
applications like counters for dual mixers or other AV measurements, but also Shera
and even Tbolt where external noise should be kept to a minimum. When you
chase 1 E-14, isolation is key and I always like to err on the cautious
side and as I stated we use blue tooth or USB but in the case of USB there
are always H11 in the circuit. Some still like to use RS 232 and the
subject came up and I have on my boards H11's like on the counter Corby uses
but he ended up using an external power source and I like to eliminate that
requirement. David had the right answer using the power that the RS 232
mouse uses out of a DB 9, started looking but I do not have one any more
and I can not find any data.
Bert
In a message dated 7/25/2013 2:48:43 P.M. Eastern Daylight Time,
marks@non-stop.com.au writes:
Hi Bert,
I am sure your circuit is clear in your head, but would you mind
attaching detail?
You have perked my interest with the "low-noise" keyword ;)
-marki
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of EWKehren@aol.com
Sent: Thursday, 25 July 2013 11:39 PM
To: time-nuts@febo.com
Subject: [time-nuts] RS 232
Since joining time nuts over four years ago I have not used a single
MAX
232 chip. Two reasons MAX do not give me isolation and do generate
noise
in critical applications. I prefer the use of two H11 opto couplers
which
work perfect. On the receiving end the diode along with a current
limiter
and blocking diode for the negative level works perfect. On the output
side
a power source is needed. If one uses an USB adapter it does have the
- 5
volt which again works perfect. How ever many prefer to use RS 232
direct and that is why I hope to get some comments and suggestions from
the
list. Corby used on our counter circuit that he described a separate
power
source.
Present MAX circuits use a + 1.4 volt threshold but considering legacy
the question is what should the voltage swing be to make it compatible
for
most PC's and what options exist to get the necessary voltage. In the
past
other pins on the RS 232 port where an ideal power source. Still an
option?
Bert Kehren
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Hi
In order to get voltages from the other pins on the D connector:
- You have to program them to be in the "correct" state (either high or low)
- They have to be present on the "driver" side (usually, but not always true)
- They need to be > 3 V (diode drops etc…)
- They need to supply enough current (as in no isolating resistors, usually true)
- You need to have two of them to spare that meet these criteria (one positive and one negative)
Its a little like rolling dice, sometimes it will work, sometimes it won't work.
Bob
On Jul 26, 2013, at 7:01 AM, EWKehren@aol.com wrote:
Since there is repeated request for the circuit se attachment. My question
is what can be done to get a positive voltage from some of the other unused
pins of the DB 9 connector. What is needed is any where from 3 to 15 volt.
Diodes work with 1 mA but I set Rx for 2 mA. Any thing else look at H11
data sheet.
Bert Kehren
In a message dated 7/26/2013 4:06:37 A.M. Eastern Daylight Time,
rexa@sonic.net writes:
FWIW, it was clear as mud for me too.
Bert began with, "Since joining time nuts over four years ago I have
not used a single MAX
232 chip. Two reasons MAX do not give me isolation and do generate noise
in critical applications."
From that I took that he was doing RS232 using opto isolators. That
implies + and - voltages to me. Where do they come from and where are
they relative to the isolation boundary? If the goal is really
isolation, how do these supplies get isolated? If the noise is cured by
isolation, these details seem important as the supplies need isolation
too. Maybe the switcher in the MAX232 is causing the noise. Then how do
we get a negative supply from, say, +5V without the noise? Then, maybe
he was saying RS232 sucks and this other way (not RS232 compatible)
works better.
The word picture of Bert's solution, which provided more details, left
me less much less than clear too. Maybe I'm just not up on circuit
shorthand terminology enough to follow what sort of current limiter is
limiting what current to what, and what is being blocked by a diode from
which negative level. Not really sure if I even got the big picture of
what he is describing. Is it an isolated equivalent of a MAX232
interface or something else that wouldn't talk to an RS232 device?
So, more clarification, or possibly that picture (~= 1k words) might
help. Or maybe I'm just obtuse and everyone else is getting it. (Seems
Marki may also be in the confused camp.)
On 7/25/2013 3:34 PM, Mark C. Stephens wrote:
Although your description,
" I prefer the use of two H11 opto couplers which
work perfect. On the receiving end the diode along with a current
limiter
and blocking diode for the negative level works perfect. On the output
side
a power source is needed." Is a perfect circuit description, I'd be
more confident with a schematic :)
--marki
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of EWKehren@aol.com
Sent: Friday, 26 July 2013 5:32 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] RS 232
I do not understand your question, I am referring to low noise
applications like counters for dual mixers or other AV measurements, but also Shera
and even Tbolt where external noise should be kept to a minimum. When you
chase 1 E-14, isolation is key and I always like to err on the cautious
side and as I stated we use blue tooth or USB but in the case of USB there
are always H11 in the circuit. Some still like to use RS 232 and the
subject came up and I have on my boards H11's like on the counter Corby uses
but he ended up using an external power source and I like to eliminate that
requirement. David had the right answer using the power that the RS 232
mouse uses out of a DB 9, started looking but I do not have one any more
and I can not find any data.
Bert
In a message dated 7/25/2013 2:48:43 P.M. Eastern Daylight Time,
marks@non-stop.com.au writes:
Hi Bert,
I am sure your circuit is clear in your head, but would you mind
attaching detail?
You have perked my interest with the "low-noise" keyword ;)
-marki
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of EWKehren@aol.com
Sent: Thursday, 25 July 2013 11:39 PM
To: time-nuts@febo.com
Subject: [time-nuts] RS 232
Since joining time nuts over four years ago I have not used a single
MAX
232 chip. Two reasons MAX do not give me isolation and do generate
noise
in critical applications. I prefer the use of two H11 opto couplers
which
work perfect. On the receiving end the diode along with a current
limiter
and blocking diode for the negative level works perfect. On the output
side
a power source is needed. If one uses an USB adapter it does have the
- 5
volt which again works perfect. How ever many prefer to use RS 232
direct and that is why I hope to get some comments and suggestions from
the
list. Corby used on our counter circuit that he described a separate
power
source.
Present MAX circuits use a + 1.4 volt threshold but considering legacy
the question is what should the voltage swing be to make it compatible
for
most PC's and what options exist to get the necessary voltage. In the
past
other pins on the RS 232 port where an ideal power source. Still an
option?
Bert Kehren
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
<H11 opto.pdf>_______________________________________________
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Hi,
#5 is one of the reasons I preferred not to take the signal negative. I suppose it depends on the situation, but for the spitting data into a pc I used to find that a 0 to 5v or so signal powered from a control line almost always worked. The most common problem was either a faulty com port or an optocoupler circuit that did not have enough gain to pull the line close to 0v. ( that was a while ago though - not so much 'legacy' as 'vintage'! )
Angus.
From: "Bob Camp"
To: "Discussion of precise time and frequency measurement"
Sent: July 26, 2013 1:37 PM
Subject: Re: [time-nuts] RS 232
Hi
In order to get voltages from the other pins on the D connector:
- You have to program them to be in the "correct" state (either high or low)
- They have to be present on the "driver" side (usually, but not always true)
- They need to be > 3 V (diode drops etc…)
- They need to supply enough current (as in no isolating resistors, usually true)
- You need to have two of them to spare that meet these criteria (one positive and one negative)
Its a little like rolling dice, sometimes it will work, sometimes it won't work.
Bob
On Jul 26, 2013, at 7:01 AM, EWKehren@aol.com wrote:
Since there is repeated request for the circuit se attachment. My question
is what can be done to get a positive voltage from some of the other unused
pins of the DB 9 connector. What is needed is any where from 3 to 15 volt.
Diodes work with 1 mA but I set Rx for 2 mA. Any thing else look at H11
data sheet.
Bert Kehren
In a message dated 7/26/2013 4:06:37 A.M. Eastern Daylight Time,
rexa@sonic.net writes:
FWIW, it was clear as mud for me too.
Bert began with, "Since joining time nuts over four years ago I have
not used a single MAX
232 chip. Two reasons MAX do not give me isolation and do generate noise
in critical applications."
From that I took that he was doing RS232 using opto isolators. That
implies + and - voltages to me. Where do they come from and where are
they relative to the isolation boundary? If the goal is really
isolation, how do these supplies get isolated? If the noise is cured by
isolation, these details seem important as the supplies need isolation
too. Maybe the switcher in the MAX232 is causing the noise. Then how do
we get a negative supply from, say, +5V without the noise? Then, maybe
he was saying RS232 sucks and this other way (not RS232 compatible)
works better.
The word picture of Bert's solution, which provided more details, left
me less much less than clear too. Maybe I'm just not up on circuit
shorthand terminology enough to follow what sort of current limiter is
limiting what current to what, and what is being blocked by a diode from
which negative level. Not really sure if I even got the big picture of
what he is describing. Is it an isolated equivalent of a MAX232
interface or something else that wouldn't talk to an RS232 device?
So, more clarification, or possibly that picture (~= 1k words) might
help. Or maybe I'm just obtuse and everyone else is getting it. (Seems
Marki may also be in the confused camp.)
On 7/25/2013 3:34 PM, Mark C. Stephens wrote:
Although your description,
" I prefer the use of two H11 opto couplers which
work perfect. On the receiving end the diode along with a current
limiter
and blocking diode for the negative level works perfect. On the output
side
a power source is needed." Is a perfect circuit description, I'd be
more confident with a schematic :)
--marki
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of EWKehren@aol.com
Sent: Friday, 26 July 2013 5:32 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] RS 232
I do not understand your question, I am referring to low noise
applications like counters for dual mixers or other AV measurements, but also Shera
and even Tbolt where external noise should be kept to a minimum. When you
chase 1 E-14, isolation is key and I always like to err on the cautious
side and as I stated we use blue tooth or USB but in the case of USB there
are always H11 in the circuit. Some still like to use RS 232 and the
subject came up and I have on my boards H11's like on the counter Corby uses
but he ended up using an external power source and I like to eliminate that
requirement. David had the right answer using the power that the RS 232
mouse uses out of a DB 9, started looking but I do not have one any more
and I can not find any data.
Bert
In a message dated 7/25/2013 2:48:43 P.M. Eastern Daylight Time,
marks@non-stop.com.au writes:
Hi Bert,
I am sure your circuit is clear in your head, but would you mind
attaching detail?
You have perked my interest with the "low-noise" keyword ;)
-marki
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of EWKehren@aol.com
Sent: Thursday, 25 July 2013 11:39 PM
To: time-nuts@febo.com
Subject: [time-nuts] RS 232
Since joining time nuts over four years ago I have not used a single
MAX
232 chip. Two reasons MAX do not give me isolation and do generate
noise
in critical applications. I prefer the use of two H11 opto couplers
which
work perfect. On the receiving end the diode along with a current
limiter
and blocking diode for the negative level works perfect. On the output
side
a power source is needed. If one uses an USB adapter it does have the
- 5
volt which again works perfect. How ever many prefer to use RS 232
direct and that is why I hope to get some comments and suggestions from
the
list. Corby used on our counter circuit that he described a separate
power
source.
Present MAX circuits use a + 1.4 volt threshold but considering legacy
the question is what should the voltage swing be to make it compatible
for
most PC's and what options exist to get the necessary voltage. In the
past
other pins on the RS 232 port where an ideal power source. Still an
option?
Bert Kehren
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Hi
The gotcha with "standard" RS-232 is that the range from -3 to +3 volts is defined as "undefined". In other words, a negative should be below -3V and a positive should be above +3 volts. Indeed most (but not all) chips count zero as a negative. A few have hysteresis and others have some odd thresholds.
Bob
On Jul 26, 2013, at 12:14 PM, Angus not.again@btinternet.com wrote:
Hi,
#5 is one of the reasons I preferred not to take the signal negative. I suppose it depends on the situation, but for the spitting data into a pc I used to find that a 0 to 5v or so signal powered from a control line almost always worked. The most common problem was either a faulty com port or an optocoupler circuit that did not have enough gain to pull the line close to 0v. ( that was a while ago though - not so much 'legacy' as 'vintage'! )
Angus.
From: "Bob Camp"
To: "Discussion of precise time and frequency measurement"
Sent: July 26, 2013 1:37 PM
Subject: Re: [time-nuts] RS 232
Hi
In order to get voltages from the other pins on the D connector:
- You have to program them to be in the "correct" state (either high or low)
- They have to be present on the "driver" side (usually, but not always true)
- They need to be > 3 V (diode drops etc…)
- They need to supply enough current (as in no isolating resistors, usually true)
- You need to have two of them to spare that meet these criteria (one positive and one negative)
Its a little like rolling dice, sometimes it will work, sometimes it won't work.
Bob
On Jul 26, 2013, at 7:01 AM, EWKehren@aol.com wrote:
Since there is repeated request for the circuit se attachment. My question
is what can be done to get a positive voltage from some of the other unused
pins of the DB 9 connector. What is needed is any where from 3 to 15 volt.
Diodes work with 1 mA but I set Rx for 2 mA. Any thing else look at H11
data sheet.
Bert Kehren
In a message dated 7/26/2013 4:06:37 A.M. Eastern Daylight Time,
rexa@sonic.net writes:
FWIW, it was clear as mud for me too.
Bert began with, "Since joining time nuts over four years ago I have
not used a single MAX
232 chip. Two reasons MAX do not give me isolation and do generate noise
in critical applications."
From that I took that he was doing RS232 using opto isolators. That
implies + and - voltages to me. Where do they come from and where are
they relative to the isolation boundary? If the goal is really
isolation, how do these supplies get isolated? If the noise is cured by
isolation, these details seem important as the supplies need isolation
too. Maybe the switcher in the MAX232 is causing the noise. Then how do
we get a negative supply from, say, +5V without the noise? Then, maybe
he was saying RS232 sucks and this other way (not RS232 compatible)
works better.
The word picture of Bert's solution, which provided more details, left
me less much less than clear too. Maybe I'm just not up on circuit
shorthand terminology enough to follow what sort of current limiter is
limiting what current to what, and what is being blocked by a diode from
which negative level. Not really sure if I even got the big picture of
what he is describing. Is it an isolated equivalent of a MAX232
interface or something else that wouldn't talk to an RS232 device?
So, more clarification, or possibly that picture (~= 1k words) might
help. Or maybe I'm just obtuse and everyone else is getting it. (Seems
Marki may also be in the confused camp.)
On 7/25/2013 3:34 PM, Mark C. Stephens wrote:
Although your description,
" I prefer the use of two H11 opto couplers which
work perfect. On the receiving end the diode along with a current
limiter
and blocking diode for the negative level works perfect. On the output
side
a power source is needed." Is a perfect circuit description, I'd be
more confident with a schematic :)
--marki
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of EWKehren@aol.com
Sent: Friday, 26 July 2013 5:32 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] RS 232
I do not understand your question, I am referring to low noise
applications like counters for dual mixers or other AV measurements, but also Shera
and even Tbolt where external noise should be kept to a minimum. When you
chase 1 E-14, isolation is key and I always like to err on the cautious
side and as I stated we use blue tooth or USB but in the case of USB there
are always H11 in the circuit. Some still like to use RS 232 and the
subject came up and I have on my boards H11's like on the counter Corby uses
but he ended up using an external power source and I like to eliminate that
requirement. David had the right answer using the power that the RS 232
mouse uses out of a DB 9, started looking but I do not have one any more
and I can not find any data.
Bert
In a message dated 7/25/2013 2:48:43 P.M. Eastern Daylight Time,
marks@non-stop.com.au writes:
Hi Bert,
I am sure your circuit is clear in your head, but would you mind
attaching detail?
You have perked my interest with the "low-noise" keyword ;)
-marki
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of EWKehren@aol.com
Sent: Thursday, 25 July 2013 11:39 PM
To: time-nuts@febo.com
Subject: [time-nuts] RS 232
Since joining time nuts over four years ago I have not used a single
MAX
232 chip. Two reasons MAX do not give me isolation and do generate
noise
in critical applications. I prefer the use of two H11 opto couplers
which
work perfect. On the receiving end the diode along with a current
limiter
and blocking diode for the negative level works perfect. On the output
side
a power source is needed. If one uses an USB adapter it does have the
- 5
volt which again works perfect. How ever many prefer to use RS 232
direct and that is why I hope to get some comments and suggestions from
the
list. Corby used on our counter circuit that he described a separate
power
source.
Present MAX circuits use a + 1.4 volt threshold but considering legacy
the question is what should the voltage swing be to make it compatible
for
most PC's and what options exist to get the necessary voltage. In the
past
other pins on the RS 232 port where an ideal power source. Still an
option?
Bert Kehren
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
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I believe the trend for the last 10 years has been to use a positive threshold. I mess with serial ports all the time professionally and not and I do not remember the last time I saw one that did not work with a positive threshold.
Didier KO4BB
Bob Camp lists@rtty.us wrote:
Hi
The gotcha with "standard" RS-232 is that the range from -3 to +3 volts
is defined as "undefined". In other words, a negative should be below
-3V and a positive should be above +3 volts. Indeed most (but not all)
chips count zero as a negative. A few have hysteresis and others have
some odd thresholds.
Bob
On Jul 26, 2013, at 12:14 PM, Angus not.again@btinternet.com wrote:
Hi,
#5 is one of the reasons I preferred not to take the signal negative.
I suppose it depends on the situation, but for the spitting data into a
pc I used to find that a 0 to 5v or so signal powered from a control
line almost always worked. The most common problem was either a faulty
com port or an optocoupler circuit that did not have enough gain to
pull the line close to 0v. ( that was a while ago though - not so much
'legacy' as 'vintage'! )
Angus.
From: "Bob Camp"
To: "Discussion of precise time and frequency measurement"
Sent: July 26, 2013 1:37 PM
Subject: Re: [time-nuts] RS 232
Hi
In order to get voltages from the other pins on the D connector:
- You have to program them to be in the "correct" state (either high
or low)
- They have to be present on the "driver" side (usually, but not
always true)
- They need to be > 3 V (diode drops etc…)
- They need to supply enough current (as in no isolating resistors,
usually true)
- You need to have two of them to spare that meet these criteria
(one positive and one negative)
Its a little like rolling dice, sometimes it will work, sometimes it
won't work.
Bob
On Jul 26, 2013, at 7:01 AM, EWKehren@aol.com wrote:
Since there is repeated request for the circuit se attachment. My
question
is what can be done to get a positive voltage from some of the other
unused
pins of the DB 9 connector. What is needed is any where from 3 to
15 volt.
Diodes work with 1 mA but I set Rx for 2 mA. Any thing else look at
H11
data sheet.
Bert Kehren
In a message dated 7/26/2013 4:06:37 A.M. Eastern Daylight Time,
rexa@sonic.net writes:
FWIW, it was clear as mud for me too.
Bert began with, "Since joining time nuts over four years ago I
have
not used a single MAX
232 chip. Two reasons MAX do not give me isolation and do generate
noise
in critical applications."
From that I took that he was doing RS232 using opto isolators. That
implies + and - voltages to me. Where do they come from and where
are
they relative to the isolation boundary? If the goal is really
isolation, how do these supplies get isolated? If the noise is
cured by
isolation, these details seem important as the supplies need
isolation
too. Maybe the switcher in the MAX232 is causing the noise. Then
how do
we get a negative supply from, say, +5V without the noise? Then,
maybe
he was saying RS232 sucks and this other way (not RS232 compatible)
works better.
The word picture of Bert's solution, which provided more details,
left
me less much less than clear too. Maybe I'm just not up on circuit
shorthand terminology enough to follow what sort of current limiter
is
limiting what current to what, and what is being blocked by a diode
from
which negative level. Not really sure if I even got the big picture
of
what he is describing. Is it an isolated equivalent of a MAX232
interface or something else that wouldn't talk to an RS232 device?
So, more clarification, or possibly that picture (~= 1k words)
might
help. Or maybe I'm just obtuse and everyone else is getting it.
(Seems
Marki may also be in the confused camp.)
On 7/25/2013 3:34 PM, Mark C. Stephens wrote:
Although your description,
" I prefer the use of two H11 opto couplers which
work perfect. On the receiving end the diode along with a current
limiter
and blocking diode for the negative level works perfect. On the
output
side
a power source is needed." Is a perfect circuit description, I'd
be
more confident with a schematic :)
[mailto:time-nuts-bounces@febo.com] On
Behalf Of EWKehren@aol.com
Sent: Friday, 26 July 2013 5:32 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] RS 232
I do not understand your question, I am referring to low noise
applications like counters for dual mixers or other AV
measurements, but also Shera
and even Tbolt where external noise should be kept to a minimum.
When you
chase 1 E-14, isolation is key and I always like to err on the
cautious
side and as I stated we use blue tooth or USB but in the case of
USB there
are always H11 in the circuit. Some still like to use RS 232 and
the
subject came up and I have on my boards H11's like on the counter
Corby uses
but he ended up using an external power source and I like to
eliminate that
requirement. David had the right answer using the power that the RS
232
mouse uses out of a DB 9, started looking but I do not have one any
more
and I can not find any data.
Bert
In a message dated 7/25/2013 2:48:43 P.M. Eastern Daylight Time,
marks@non-stop.com.au writes:
Hi Bert,
I am sure your circuit is clear in your head, but would you mind
attaching detail?
You have perked my interest with the "low-noise" keyword ;)
-marki
-----Original Message-----
From: time-nuts-bounces@febo.com
[mailto:time-nuts-bounces@febo.com] On
Behalf Of EWKehren@aol.com
Sent: Thursday, 25 July 2013 11:39 PM
To: time-nuts@febo.com
Subject: [time-nuts] RS 232
Since joining time nuts over four years ago I have not used a
single
MAX
232 chip. Two reasons MAX do not give me isolation and do
generate
noise
in critical applications. I prefer the use of two H11 opto
couplers
which
work perfect. On the receiving end the diode along with a current
limiter
and blocking diode for the negative level works perfect. On the
output
side
a power source is needed. If one uses an USB adapter it does
have the
- 5
volt which again works perfect. How ever many prefer to use RS
232
direct and that is why I hope to get some comments and
suggestions from
the
list. Corby used on our counter circuit that he described a
separate
power
source.
Present MAX circuits use a + 1.4 volt threshold but considering
legacy
the question is what should the voltage swing be to make it
compatible
for
most PC's and what options exist to get the necessary voltage. In
the
past
other pins on the RS 232 port where an ideal power source. Still
an
option?
Bert Kehren
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
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time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
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To unsubscribe, go to
and follow the instructions there.
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To unsubscribe, go to
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--
Sent from my Motorola Droid Razr 4G LTE wireless tracker while I do other things.
Hi
I can't say if they were more than 10 years old or not, but I have seen some ports that do not work reliably with a 0-5V signal in the last few years.
Bob
On Jul 26, 2013, at 3:58 PM, Didier Juges shalimr9@gmail.com wrote:
I believe the trend for the last 10 years has been to use a positive threshold. I mess with serial ports all the time professionally and not and I do not remember the last time I saw one that did not work with a positive threshold.
Didier KO4BB
Bob Camp lists@rtty.us wrote:
Hi
The gotcha with "standard" RS-232 is that the range from -3 to +3 volts
is defined as "undefined". In other words, a negative should be below
-3V and a positive should be above +3 volts. Indeed most (but not all)
chips count zero as a negative. A few have hysteresis and others have
some odd thresholds.
Bob
On Jul 26, 2013, at 12:14 PM, Angus not.again@btinternet.com wrote:
Hi,
#5 is one of the reasons I preferred not to take the signal negative.
I suppose it depends on the situation, but for the spitting data into a
pc I used to find that a 0 to 5v or so signal powered from a control
line almost always worked. The most common problem was either a faulty
com port or an optocoupler circuit that did not have enough gain to
pull the line close to 0v. ( that was a while ago though - not so much
'legacy' as 'vintage'! )
Angus.
From: "Bob Camp"
To: "Discussion of precise time and frequency measurement"
Sent: July 26, 2013 1:37 PM
Subject: Re: [time-nuts] RS 232
Hi
In order to get voltages from the other pins on the D connector:
- You have to program them to be in the "correct" state (either high
or low)
- They have to be present on the "driver" side (usually, but not
always true)
- They need to be > 3 V (diode drops etc…)
- They need to supply enough current (as in no isolating resistors,
usually true)
- You need to have two of them to spare that meet these criteria
(one positive and one negative)
Its a little like rolling dice, sometimes it will work, sometimes it
won't work.
Bob
On Jul 26, 2013, at 7:01 AM, EWKehren@aol.com wrote:
Since there is repeated request for the circuit se attachment. My
question
is what can be done to get a positive voltage from some of the other
unused
pins of the DB 9 connector. What is needed is any where from 3 to
15 volt.
Diodes work with 1 mA but I set Rx for 2 mA. Any thing else look at
H11
data sheet.
Bert Kehren
In a message dated 7/26/2013 4:06:37 A.M. Eastern Daylight Time,
rexa@sonic.net writes:
FWIW, it was clear as mud for me too.
Bert began with, "Since joining time nuts over four years ago I
have
not used a single MAX
232 chip. Two reasons MAX do not give me isolation and do generate
noise
in critical applications."
From that I took that he was doing RS232 using opto isolators. That
implies + and - voltages to me. Where do they come from and where
are
they relative to the isolation boundary? If the goal is really
isolation, how do these supplies get isolated? If the noise is
cured by
isolation, these details seem important as the supplies need
isolation
too. Maybe the switcher in the MAX232 is causing the noise. Then
how do
we get a negative supply from, say, +5V without the noise? Then,
maybe
he was saying RS232 sucks and this other way (not RS232 compatible)
works better.
The word picture of Bert's solution, which provided more details,
left
me less much less than clear too. Maybe I'm just not up on circuit
shorthand terminology enough to follow what sort of current limiter
is
limiting what current to what, and what is being blocked by a diode
from
which negative level. Not really sure if I even got the big picture
of
what he is describing. Is it an isolated equivalent of a MAX232
interface or something else that wouldn't talk to an RS232 device?
So, more clarification, or possibly that picture (~= 1k words)
might
help. Or maybe I'm just obtuse and everyone else is getting it.
(Seems
Marki may also be in the confused camp.)
On 7/25/2013 3:34 PM, Mark C. Stephens wrote:
Although your description,
" I prefer the use of two H11 opto couplers which
work perfect. On the receiving end the diode along with a current
limiter
and blocking diode for the negative level works perfect. On the
output
side
a power source is needed." Is a perfect circuit description, I'd
be
more confident with a schematic :)
[mailto:time-nuts-bounces@febo.com] On
Behalf Of EWKehren@aol.com
Sent: Friday, 26 July 2013 5:32 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] RS 232
I do not understand your question, I am referring to low noise
applications like counters for dual mixers or other AV
measurements, but also Shera
and even Tbolt where external noise should be kept to a minimum.
When you
chase 1 E-14, isolation is key and I always like to err on the
cautious
side and as I stated we use blue tooth or USB but in the case of
USB there
are always H11 in the circuit. Some still like to use RS 232 and
the
subject came up and I have on my boards H11's like on the counter
Corby uses
but he ended up using an external power source and I like to
eliminate that
requirement. David had the right answer using the power that the RS
232
mouse uses out of a DB 9, started looking but I do not have one any
more
and I can not find any data.
Bert
In a message dated 7/25/2013 2:48:43 P.M. Eastern Daylight Time,
marks@non-stop.com.au writes:
Hi Bert,
I am sure your circuit is clear in your head, but would you mind
attaching detail?
You have perked my interest with the "low-noise" keyword ;)
-marki
-----Original Message-----
From: time-nuts-bounces@febo.com
[mailto:time-nuts-bounces@febo.com] On
Behalf Of EWKehren@aol.com
Sent: Thursday, 25 July 2013 11:39 PM
To: time-nuts@febo.com
Subject: [time-nuts] RS 232
Since joining time nuts over four years ago I have not used a
single
MAX
232 chip. Two reasons MAX do not give me isolation and do
generate
noise
in critical applications. I prefer the use of two H11 opto
couplers
which
work perfect. On the receiving end the diode along with a current
limiter
and blocking diode for the negative level works perfect. On the
output
side
a power source is needed. If one uses an USB adapter it does
have the
- 5
volt which again works perfect. How ever many prefer to use RS
232
direct and that is why I hope to get some comments and
suggestions from
the
list. Corby used on our counter circuit that he described a
separate
power
source.
Present MAX circuits use a + 1.4 volt threshold but considering
legacy
the question is what should the voltage swing be to make it
compatible
for
most PC's and what options exist to get the necessary voltage. In
the
past
other pins on the RS 232 port where an ideal power source. Still
an
option?
Bert Kehren
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
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and follow the instructions there.
--
Sent from my Motorola Droid Razr 4G LTE wireless tracker while I do other things.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
The old MC1489's and 1489A's had both positive and negative
thresholds (about +/- 1.5V.. not quite correct, but better
than nothing), and as such wouldn't work with a 0 to 5V signal.
Then along came the IBM-PC, with its comport card that had both
20ma current loop, and RS232 implemented using single transistor
circuits, and the die was cast.
The MAX232 also implemented the standard incorrectly by leaving
out the hysteresis and going with a TTL threshold.
I don't know that there has ever been an IC line receiver that
implemented RS232's thresholds correctly.
-Chuck Harris
Bob Camp wrote:
Hi
I can't say if they were more than 10 years old or not, but I have seen some ports
that do not work reliably with a 0-5V signal in the last few years.
Bob
On Jul 26, 2013, at 3:58 PM, Didier Juges shalimr9@gmail.com wrote:
I believe the trend for the last 10 years has been to use a positive threshold.
I mess with serial ports all the time professionally and not and I do not
remember the last time I saw one that did not work with a positive threshold.
Didier KO4BB
It you can figure out how to raise DTR while your application has the port open it can be a good source of power for a RS232 device.
-marki
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Bob Camp
Sent: Friday, 26 July 2013 10:37 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] RS 232
Hi
In order to get voltages from the other pins on the D connector:
- You have to program them to be in the "correct" state (either high or low)
- They have to be present on the "driver" side (usually, but not always true)
- They need to be > 3 V (diode drops etc...)
- They need to supply enough current (as in no isolating resistors, usually true)
- You need to have two of them to spare that meet these criteria (one positive and one negative)
Its a little like rolling dice, sometimes it will work, sometimes it won't work.
Bob
On Jul 26, 2013, at 7:01 AM, EWKehren@aol.com wrote:
Since there is repeated request for the circuit se attachment. My
question is what can be done to get a positive voltage from some of
the other unused pins of the DB 9 connector. What is needed is any where from 3 to 15 volt.
Diodes work with 1 mA but I set Rx for 2 mA. Any thing else look at
H11 data sheet.
Bert Kehren
In a message dated 7/26/2013 4:06:37 A.M. Eastern Daylight Time,
rexa@sonic.net writes:
FWIW, it was clear as mud for me too.
Bert began with, "Since joining time nuts over four years ago I have
not used a single MAX
232 chip. Two reasons MAX do not give me isolation and do generate noise
in critical applications."
From that I took that he was doing RS232 using opto isolators. That
implies + and - voltages to me. Where do they come from and where are
they relative to the isolation boundary? If the goal is really
isolation, how do these supplies get isolated? If the noise is cured
by isolation, these details seem important as the supplies need
isolation too. Maybe the switcher in the MAX232 is causing the noise.
Then how do we get a negative supply from, say, +5V without the
noise? Then, maybe he was saying RS232 sucks and this other way (not
RS232 compatible) works better.
The word picture of Bert's solution, which provided more details,
left me less much less than clear too. Maybe I'm just not up on
circuit shorthand terminology enough to follow what sort of current
limiter is limiting what current to what, and what is being blocked
by a diode from which negative level. Not really sure if I even got
the big picture of what he is describing. Is it an isolated
equivalent of a MAX232 interface or something else that wouldn't talk to an RS232 device?
So, more clarification, or possibly that picture (~= 1k words) might
help. Or maybe I'm just obtuse and everyone else is getting it.
(Seems Marki may also be in the confused camp.)
On 7/25/2013 3:34 PM, Mark C. Stephens wrote:
Although your description,
" I prefer the use of two H11 opto couplers which work perfect. On
the receiving end the diode along with a current
limiter
and blocking diode for the negative level works perfect. On the
output
side
a power source is needed." Is a perfect circuit description, I'd
be
more confident with a schematic :)
--marki
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com]
On
Behalf Of EWKehren@aol.com
Sent: Friday, 26 July 2013 5:32 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] RS 232
I do not understand your question, I am referring to low noise
applications like counters for dual mixers or other AV measurements,
but also Shera and even Tbolt where external noise should be kept to a minimum. When you
chase 1 E-14, isolation is key and I always like to err on the cautious
side and as I stated we use blue tooth or USB but in the case of USB
there are always H11 in the circuit. Some still like to use RS 232
and the subject came up and I have on my boards H11's like on the
counter Corby uses but he ended up using an external power source
and I like to eliminate that requirement. David had the right answer
using the power that the RS 232 mouse uses out of a DB 9, started
looking but I do not have one any more and I can not find any data.
Bert
In a message dated 7/25/2013 2:48:43 P.M. Eastern Daylight Time,
marks@non-stop.com.au writes:
Hi Bert,
I am sure your circuit is clear in your head, but would you mind
attaching detail?
You have perked my interest with the "low-noise" keyword ;)
-marki
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of EWKehren@aol.com
Sent: Thursday, 25 July 2013 11:39 PM
To: time-nuts@febo.com
Subject: [time-nuts] RS 232
Since joining time nuts over four years ago I have not used a single
MAX
232 chip. Two reasons MAX do not give me isolation and do generate
noise
in critical applications. I prefer the use of two H11 opto couplers
which
work perfect. On the receiving end the diode along with a current
limiter
and blocking diode for the negative level works perfect. On the output
side
a power source is needed. If one uses an USB adapter it does have the
- 5
volt which again works perfect. How ever many prefer to use RS 232
direct and that is why I hope to get some comments and suggestions from
the
list. Corby used on our counter circuit that he described a separate
power
source.
Present MAX circuits use a + 1.4 volt threshold but considering legacy
the question is what should the voltage swing be to make it compatible
for
most PC's and what options exist to get the necessary voltage. In the
past
other pins on the RS 232 port where an ideal power source. Still an
option?
Bert Kehren
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
<H11 opto.pdf>_______________________________________________
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To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.