Empathy List Archives

MS

Matthew Smith

Thu, Jun 5, 2008 1:26 AM

Hi Folks

Are there any issues with connecting computers to GPS modules through
USB to serial devices like the FTDI FT232R, as opposed to 'native'
serial ports? At the moment, I'm thinking in the context of an NTP
server, but am interested in a general context should I need to move to
USB-only PCs. Didn't know if there were any latency issues or anything.

Cheers

M

--
Matthew Smith
Smiffytech - Technology Consulting & Web Application Development
Business: http://www.smiffytech.com/
Personal: http://www.smiffysplace.com/
LinkedIn: http://www.linkedin.com/in/smiffy

Hi Folks Are there any issues with connecting computers to GPS modules through USB to serial devices like the FTDI FT232R, as opposed to 'native' serial ports? At the moment, I'm thinking in the context of an NTP server, but am interested in a general context should I need to move to USB-only PCs. Didn't know if there were any latency issues or anything. Cheers M -- Matthew Smith Smiffytech - Technology Consulting & Web Application Development Business: http://www.smiffytech.com/ Personal: http://www.smiffysplace.com/ LinkedIn: http://www.linkedin.com/in/smiffy

P

Prologix

Thu, Jun 5, 2008 2:45 AM

Usually, the adapters work fine. Two instances where they may not:

Devices that are powered from "unused" serial lines.
Applications that perform direct twiddling of serial lines, instead of
using host OS functions.

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Matthew Smith
Sent: Wednesday, June 04, 2008 6:26 PM
To: Time Nuts List
Subject: [time-nuts] USB to Serial Connectors for GPS Modules

Hi Folks

Are there any issues with connecting computers to GPS modules through
USB to serial devices like the FTDI FT232R, as opposed to 'native'
serial ports? At the moment, I'm thinking in the context of an NTP
server, but am interested in a general context should I need to move to
USB-only PCs. Didn't know if there were any latency issues or anything.

Cheers

M

--
Matthew Smith
Smiffytech - Technology Consulting & Web Application Development
Business: http://www.smiffytech.com/
Personal: http://www.smiffysplace.com/
LinkedIn: http://www.linkedin.com/in/smiffy

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.

Usually, the adapters work fine. Two instances where they _may_ not: 1. Devices that are powered from "unused" serial lines. 2. Applications that perform direct twiddling of serial lines, instead of using host OS functions. -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Matthew Smith Sent: Wednesday, June 04, 2008 6:26 PM To: Time Nuts List Subject: [time-nuts] USB to Serial Connectors for GPS Modules Hi Folks Are there any issues with connecting computers to GPS modules through USB to serial devices like the FTDI FT232R, as opposed to 'native' serial ports? At the moment, I'm thinking in the context of an NTP server, but am interested in a general context should I need to move to USB-only PCs. Didn't know if there were any latency issues or anything. Cheers M -- Matthew Smith Smiffytech - Technology Consulting & Web Application Development Business: http://www.smiffytech.com/ Personal: http://www.smiffysplace.com/ LinkedIn: http://www.linkedin.com/in/smiffy _______________________________________________ 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.

UB

Ulrich Bangert

Thu, Jun 5, 2008 4:28 AM

Matthew,

consider the latency times of ANYTHING on a USB provided virtual serial
connection to be in the order of 1 ms. If no serial data is send but
only status signals change their state the latency can even be higher.

Best regards
Ulrich Bangert

-----Ursprungliche Nachricht-----
Von: time-nuts-bounces@febo.com
[mailto:time-nuts-bounces@febo.com] Im Auftrag von Matthew Smith
Gesendet: Donnerstag, 5. Juni 2008 03:26
An: Time Nuts List
Betreff: [time-nuts] USB to Serial Connectors for GPS Modules

Hi Folks

Are there any issues with connecting computers to GPS modules through
USB to serial devices like the FTDI FT232R, as opposed to 'native'
serial ports? At the moment, I'm thinking in the context of an NTP
server, but am interested in a general context should I need
to move to
USB-only PCs. Didn't know if there were any latency issues
or anything.

Cheers

M

--
Matthew Smith
Smiffytech - Technology Consulting & Web Application Development
Business: http://www.smiffytech.com/
Personal: http://www.smiffysplace.com/
LinkedIn: http://www.linkedin.com/in/smiffy

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.

Matthew, consider the latency times of ANYTHING on a USB provided virtual serial connection to be in the order of 1 ms. If no serial data is send but only status signals change their state the latency can even be higher. Best regards Ulrich Bangert > -----Ursprungliche Nachricht----- > Von: time-nuts-bounces@febo.com > [mailto:time-nuts-bounces@febo.com] Im Auftrag von Matthew Smith > Gesendet: Donnerstag, 5. Juni 2008 03:26 > An: Time Nuts List > Betreff: [time-nuts] USB to Serial Connectors for GPS Modules > > > Hi Folks > > Are there any issues with connecting computers to GPS modules through > USB to serial devices like the FTDI FT232R, as opposed to 'native' > serial ports? At the moment, I'm thinking in the context of an NTP > server, but am interested in a general context should I need > to move to > USB-only PCs. Didn't know if there were any latency issues > or anything. > > Cheers > > M > > -- > Matthew Smith > Smiffytech - Technology Consulting & Web Application Development > Business: http://www.smiffytech.com/ > Personal: http://www.smiffysplace.com/ > LinkedIn: http://www.linkedin.com/in/smiffy > > _______________________________________________ > 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. >

MS

Matthew Smith

Thu, Jun 5, 2008 11:10 PM

Quoth Ulrich Bangert at 2008-06-05 13:58...

consider the latency times of ANYTHING on a USB provided virtual serial
connection to be in the order of 1 ms. If no serial data is send but
only status signals change their state the latency can even be higher.

Thanks (and to the others who responded to this). Just wanted to know
where I was.

I will make sure that I've got "real" serial ports with "real" kernel
drivers for timing applications and use USB only for non time-critical
stuff, like control messages, etc. (given a module with with 2 serial
ports and only 1 port available on the house computer, for instance.)

Cheers

M

--
Matthew Smith
Smiffytech - Technology Consulting & Web Application Development
Business: http://www.smiffytech.com/
Personal: http://www.smiffysplace.com/
LinkedIn: http://www.linkedin.com/in/smiffy

Quoth Ulrich Bangert at 2008-06-05 13:58... > consider the latency times of ANYTHING on a USB provided virtual serial > connection to be in the order of 1 ms. If no serial data is send but > only status signals change their state the latency can even be higher. Thanks (and to the others who responded to this). Just wanted to know where I was. I will make sure that I've got "real" serial ports with "real" kernel drivers for timing applications and use USB only for non time-critical stuff, like control messages, etc. (given a module with with 2 serial ports and only 1 port available on the house computer, for instance.) Cheers M -- Matthew Smith Smiffytech - Technology Consulting & Web Application Development Business: http://www.smiffytech.com/ Personal: http://www.smiffysplace.com/ LinkedIn: http://www.linkedin.com/in/smiffy

JL

Jim Lux

Thu, Jun 5, 2008 11:39 PM

At 04:10 PM 6/5/2008, Matthew Smith wrote:

Quoth Ulrich Bangert at 2008-06-05 13:58...

consider the latency times of ANYTHING on a USB provided virtual serial
connection to be in the order of 1 ms. If no serial data is send but
only status signals change their state the latency can even be higher.

Thanks (and to the others who responded to this). Just wanted to know
where I was.

I will make sure that I've got "real" serial ports with "real" kernel
drivers for timing applications and use USB only for non time-critical
stuff, like control messages, etc. (given a module with with 2 serial
ports and only 1 port available on the house computer, for instance.)

Cheers

M

I wouldn't assume that the latency on a hardware serial port,
depending on the OS, is any better than 1 ms, either.

Particularly if you are expecting the process to be something like:

value change on serial port line (Carrier Det)
interrupt from hardware
fielded by serial port ISR
blocked process waiting on CD interrupt marked as ready to run
<indeterminate time waiting for next scheduler pass>
process starts running.

While it might only take microseconds to fire up the ISR, it could be
milliseconds before your process starts to run (unless you're using
something at the device driver level?)

At 04:10 PM 6/5/2008, Matthew Smith wrote: >Quoth Ulrich Bangert at 2008-06-05 13:58... > > > consider the latency times of ANYTHING on a USB provided virtual serial > > connection to be in the order of 1 ms. If no serial data is send but > > only status signals change their state the latency can even be higher. > >Thanks (and to the others who responded to this). Just wanted to know >where I was. > >I will make sure that I've got "real" serial ports with "real" kernel >drivers for timing applications and use USB only for non time-critical >stuff, like control messages, etc. (given a module with with 2 serial >ports and only 1 port available on the house computer, for instance.) > >Cheers > >M I wouldn't assume that the latency on a hardware serial port, depending on the OS, is any better than 1 ms, either. Particularly if you are expecting the process to be something like: value change on serial port line (Carrier Det) interrupt from hardware fielded by serial port ISR blocked process waiting on CD interrupt marked as ready to run <indeterminate time waiting for next scheduler pass> process starts running. While it might only take microseconds to fire up the ISR, it could be milliseconds before your process starts to run (unless you're using something at the device driver level?)

B

bjones0@mindspring.com

Fri, Feb 20, 2009 3:03 AM

I'm tired of banging my head against the wall so I think it is time to
ask.. Is there a way to test if the serial port on the Thunderbolt
works? I know the Thunderbolt itself powers up and works (I get a
9.9999978 Mhz signal out of the 10Mhz output when it is on) but I have
been unable to talk/listen to it in Windows (tboltmon or Lady Heather)
or in Linux (even looking at the raw serial port state). I stuck my
breakout box on the line but I get no lights on the Thunderbolt side.

Thanks,
Brian

I'm tired of banging my head against the wall so I think it is time to ask.. Is there a way to test if the serial port on the Thunderbolt works? I know the Thunderbolt itself powers up and works (I get a 9.9999978 Mhz signal out of the 10Mhz output when it is on) but I have been unable to talk/listen to it in Windows (tboltmon or Lady Heather) or in Linux (even looking at the raw serial port state). I stuck my breakout box on the line but I get no lights on the Thunderbolt side. Thanks, Brian

JL

J. L. Trantham

Fri, Feb 20, 2009 3:22 AM

Brian,

I had a failure of a TAPR Thunderbolt where the 10 MHz out was present
(though not disciplined and, therefore, not 10.0000000000 MHz on my 5370B
when 'clocked' by another disciplined Thunderbolt) but there was no 1 PPS
and there was no ability to communicate via the serial port.

I have not had a chance to explore the origin of the failure but plan to at
some point. I suspect you have a similar failure to what I had. The 10 MHz
was close, like yours, but not exact.

I would be very interested in knowing what you might find as the 'failed
component'.

Thanks,

Joe

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of bjones0@mindspring.com
Sent: Thursday, February 19, 2009 9:04 PM
To: time-nuts@febo.com
Subject: [time-nuts] Thunderbolt serial port

I'm tired of banging my head against the wall so I think it is time to
ask.. Is there a way to test if the serial port on the Thunderbolt
works? I know the Thunderbolt itself powers up and works (I get a
9.9999978 Mhz signal out of the 10Mhz output when it is on) but I have
been unable to talk/listen to it in Windows (tboltmon or Lady Heather)
or in Linux (even looking at the raw serial port state). I stuck my
breakout box on the line but I get no lights on the Thunderbolt side.

Thanks,
Brian

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.

Brian, I had a failure of a TAPR Thunderbolt where the 10 MHz out was present (though not disciplined and, therefore, not 10.0000000000 MHz on my 5370B when 'clocked' by another disciplined Thunderbolt) but there was no 1 PPS and there was no ability to communicate via the serial port. I have not had a chance to explore the origin of the failure but plan to at some point. I suspect you have a similar failure to what I had. The 10 MHz was close, like yours, but not exact. I would be very interested in knowing what you might find as the 'failed component'. Thanks, Joe -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of bjones0@mindspring.com Sent: Thursday, February 19, 2009 9:04 PM To: time-nuts@febo.com Subject: [time-nuts] Thunderbolt serial port I'm tired of banging my head against the wall so I think it is time to ask.. Is there a way to test if the serial port on the Thunderbolt works? I know the Thunderbolt itself powers up and works (I get a 9.9999978 Mhz signal out of the 10Mhz output when it is on) but I have been unable to talk/listen to it in Windows (tboltmon or Lady Heather) or in Linux (even looking at the raw serial port state). I stuck my breakout box on the line but I get no lights on the Thunderbolt side. Thanks, Brian _______________________________________________ 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.

BC

Brooke Clarke

Fri, Feb 20, 2009 3:35 AM

Hi Brian:

There have been a small number of problems related to poor solder joints on U9
(RS-232 chip) or the serial connector. see:
http://www.prc68.com/I/ThunderBolt.shtml#Maint

Have Fun,

Brooke Clarke
http://www.prc68.com

bjones0@mindspring.com wrote:

I'm tired of banging my head against the wall so I think it is time to
ask.. Is there a way to test if the serial port on the Thunderbolt
works? I know the Thunderbolt itself powers up and works (I get a
9.9999978 Mhz signal out of the 10Mhz output when it is on) but I have
been unable to talk/listen to it in Windows (tboltmon or Lady Heather)
or in Linux (even looking at the raw serial port state). I stuck my
breakout box on the line but I get no lights on the Thunderbolt side.

Thanks,
Brian

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 Brian: There have been a small number of problems related to poor solder joints on U9 (RS-232 chip) or the serial connector. see: http://www.prc68.com/I/ThunderBolt.shtml#Maint Have Fun, Brooke Clarke http://www.prc68.com bjones0@mindspring.com wrote: > I'm tired of banging my head against the wall so I think it is time to > ask.. Is there a way to test if the serial port on the Thunderbolt > works? I know the Thunderbolt itself powers up and works (I get a > 9.9999978 Mhz signal out of the 10Mhz output when it is on) but I have > been unable to talk/listen to it in Windows (tboltmon or Lady Heather) > or in Linux (even looking at the raw serial port state). I stuck my > breakout box on the line but I get no lights on the Thunderbolt side. > > Thanks, > Brian > > > _______________________________________________ > 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. > >

NM

Nic McLean

Fri, Feb 20, 2009 4:33 AM

Are you using a straight through or crossover serial cable?
Nic

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Brooke Clarke
Sent: Friday, 20 February 2009 2:35 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Thunderbolt serial port

Hi Brian:

There have been a small number of problems related to poor solder joints on
U9
(RS-232 chip) or the serial connector. see:
http://www.prc68.com/I/ThunderBolt.shtml#Maint

Have Fun,

Brooke Clarke
http://www.prc68.com

bjones0@mindspring.com wrote:

I'm tired of banging my head against the wall so I think it is time to
ask.. Is there a way to test if the serial port on the Thunderbolt
works? I know the Thunderbolt itself powers up and works (I get a
9.9999978 Mhz signal out of the 10Mhz output when it is on) but I have
been unable to talk/listen to it in Windows (tboltmon or Lady Heather)
or in Linux (even looking at the raw serial port state). I stuck my
breakout box on the line but I get no lights on the Thunderbolt side.

Thanks,
Brian

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.

Are you using a straight through or crossover serial cable? Nic -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Brooke Clarke Sent: Friday, 20 February 2009 2:35 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Thunderbolt serial port Hi Brian: There have been a small number of problems related to poor solder joints on U9 (RS-232 chip) or the serial connector. see: http://www.prc68.com/I/ThunderBolt.shtml#Maint Have Fun, Brooke Clarke http://www.prc68.com bjones0@mindspring.com wrote: > I'm tired of banging my head against the wall so I think it is time to > ask.. Is there a way to test if the serial port on the Thunderbolt > works? I know the Thunderbolt itself powers up and works (I get a > 9.9999978 Mhz signal out of the 10Mhz output when it is on) but I have > been unable to talk/listen to it in Windows (tboltmon or Lady Heather) > or in Linux (even looking at the raw serial port state). I stuck my > breakout box on the line but I get no lights on the Thunderbolt side. > > Thanks, > Brian > > > _______________________________________________ > 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.

B

bjones0@mindspring.com

Fri, Feb 20, 2009 11:01 AM

Nic - I have tried several of each... and even tried using the breakout
box to create a crossover/null modem but no luck.

Brooke -
Thanks for the insight. I will tear in to it this weekend and see what
I can find.

Thanks.

-Brian

On Fri, 2009-02-20 at 15:33 +1100, Nic McLean wrote:

Are you using a straight through or crossover serial cable?
Nic

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Brooke Clarke
Sent: Friday, 20 February 2009 2:35 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Thunderbolt serial port

Hi Brian:

There have been a small number of problems related to poor solder joints on
U9
(RS-232 chip) or the serial connector. see:
http://www.prc68.com/I/ThunderBolt.shtml#Maint

Have Fun,

Brooke Clarke
http://www.prc68.com

bjones0@mindspring.com wrote:

I'm tired of banging my head against the wall so I think it is time to
ask.. Is there a way to test if the serial port on the Thunderbolt
works? I know the Thunderbolt itself powers up and works (I get a
9.9999978 Mhz signal out of the 10Mhz output when it is on) but I have
been unable to talk/listen to it in Windows (tboltmon or Lady Heather)
or in Linux (even looking at the raw serial port state). I stuck my
breakout box on the line but I get no lights on the Thunderbolt side.

Thanks,
Brian

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.

Nic - I have tried several of each... and even tried using the breakout box to create a crossover/null modem but no luck. Brooke - Thanks for the insight. I will tear in to it this weekend and see what I can find. Thanks. -Brian On Fri, 2009-02-20 at 15:33 +1100, Nic McLean wrote: > Are you using a straight through or crossover serial cable? > Nic > > -----Original Message----- > From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On > Behalf Of Brooke Clarke > Sent: Friday, 20 February 2009 2:35 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Thunderbolt serial port > > Hi Brian: > > There have been a small number of problems related to poor solder joints on > U9 > (RS-232 chip) or the serial connector. see: > http://www.prc68.com/I/ThunderBolt.shtml#Maint > > Have Fun, > > Brooke Clarke > http://www.prc68.com > > bjones0@mindspring.com wrote: > > I'm tired of banging my head against the wall so I think it is time to > > ask.. Is there a way to test if the serial port on the Thunderbolt > > works? I know the Thunderbolt itself powers up and works (I get a > > 9.9999978 Mhz signal out of the 10Mhz output when it is on) but I have > > been unable to talk/listen to it in Windows (tboltmon or Lady Heather) > > or in Linux (even looking at the raw serial port state). I stuck my > > breakout box on the line but I get no lights on the Thunderbolt side. > > > > Thanks, > > Brian > > > > > > _______________________________________________ > > 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.

time-nuts@lists.febo.com

USB to Serial Connectors for GPS Modules