Welcome to the crazy world of RS232.
A modem is DCE, a teleprinter/terminal is DTE.
Anything else is uncertain.
Get yourself a link tester/ breakout/patch box, and a set of 9/25 pin
adapters, and have fun!
These days identify TX and RX pins and connectors appropriately.
Hopefully you won't have to deal with full RS232 hardware handshaking,
(CD,DTR,DSR,TTS,CTS)
Stephen Tompsett

On Mon, 30 Dec 2024, 18:29 rbenward--- via time-nuts, <
time-nuts@lists.febo.com> wrote:

Bob,

I expect there's easier sample projects you can try and succeed on before
diving into your larger Z3801A problem without enough relevant experience.

I vaguely recall setting up a parallel cable DB-25 connection between two
Windows 3.1 computers for file transfer, as one ancient example.

We use various radios for SCADA at work, and all of the older ones used
serial and we had significant DTE-DCE challenges on larger networks and on
varied applications.

Perhaps you can volunteer your time to inspect your local club's APRS
digipeater setup, offering to refine it, and learning along the way too.
Applying those findings might make your own troubleshooting a bit easier.

Adam VE6WMR

On Mon, Dec 30, 2024, 12:49 p.m. Stephen Tompsett via time-nuts <
time-nuts@lists.febo.com> wrote:

This is why I maintain an HP 4952A and a wide assortment of gender
changers, BOBs, DB9/25 converters, etc.  I can sort out anything.

Best regards

Mahlon - N4ZK

On Mon, Dec 30, 2024, 1:50 PM Stephen Tompsett via time-nuts <
time-nuts@lists.febo.com> wrote:

Bob:

1. I have several Z3805As with Synergy SSR-VP-UT+ receivers #
   16U54523G-B1 (having replaced the original Motorola ones).
2. I have an eBay-sourced "Serial Port Adapter D9/D25" on each Z3805A's
   rear-panel female DB25. This adapter is male DB9/male DB25 with only 9 pins
   populated on the DB25 side.
3. I avoid 25-pin cables wherever possible, and stick with 9-pinners.
4. Whenever I design something that requires / has an RS232 port, I pin
   it out as DTE, with male DB9s.This means that serial out (SO) is on pin 3,
   and serial in (SI) is on pin 2.
5. Hence, whenever I need to connect something (typically to a PC or to
   a USB-to-serial adapter), I use a null-modem cable (DB9 female on each end,
   functioning as a "crossover" cable).
6. This way, it's all easier than thinking :-)

--Andrew

Andrew E. Kalman, Ph.D.

On Sun, Dec 29, 2024 at 2:09 PM rbenward--- via time-nuts <
time-nuts@lists.febo.com> wrote:

Adam,
I am not sure what you mean by relevant experience.  I am not trouble shooting the RS232.  My GPSDOs are working.  I am looking to purchase more equipment and looking at manuals to understand what I need.  I posted here looking for other's experiences RS232 & DTE,DCE.  It seems I am not alone.  I am a retired EE by trade and it bothers me that I cannot get consensus from the internet on the pinout and naming convention of a simple RS232 port.  I find it disturbing that HP/Symmetricom thinks a computer is DCE.  I believe the Z380x are DTE equipment even though the connectors are female like DCE modems.  According to the spec, any female DE9 or DB25 female is a DCE.  Male pins are DTE.  They don't provide the cable, and hopefully you buy a null cable, because chances are your computer is DTE, not DCE (fig1-2 in the manual).  Unless of course they got it backwards.  Do you see what I am getting at?

I also find it disturbing that Startech can't get the pin numbers right on their serial port adapter manual (I did more research).  Adapters is all they do.  Their other RS232 adapter manuals got it right.  I picked up the wrong manual.

Simply, old habits are hard to kill.  I look at data sheets and then design.  I don't like buying things and then try and slap them together.  I've been burned to many times that way.  It seems like after all this time there is still no convention.

My take from all of this: anything that appears to convert one signal into another, RS232 to PSTN (our classic phone modem), or a RS232 to RS422 converter, any that extends a signal, is a DCE.  Almost everything else is a DTE. Excluded of course is the USB to RS232.  Startech makes theirs look like a DTE.  Waveshare has both flavors. I actually found one RS232 to RS422 converter that was labeled "DCE".

A nice treatise covering RS232 for those needing a refresher:
https://www.advantech.com/en/resources/white-papers/e7e269e7-78b9-4848-96d1-aa7b6acca0d4

Bob

-----Original Message-----
From: Adam Kuzych via time-nuts time-nuts@lists.febo.com
Sent: Monday, December 30, 2024 2:58 PM
To: Discussion of precise time and frequency measurement time-nuts@lists.febo.com
Cc: Adam Kuzych akuzych@gmail.com
Subject: [time-nuts] Re: RS232
Importance: High

Bob,

I expect there's easier sample projects you can try and succeed on before diving into your larger Z3801A problem without enough relevant experience.

I vaguely recall setting up a parallel cable DB-25 connection between two Windows 3.1 computers for file transfer, as one ancient example.

We use various radios for SCADA at work, and all of the older ones used serial and we had significant DTE-DCE challenges on larger networks and on varied applications.

Perhaps you can volunteer your time to inspect your local club's APRS digipeater setup, offering to refine it, and learning along the way too.
Applying those findings might make your own troubleshooting a bit easier.

Adam VE6WMR

On Mon, Dec 30, 2024, 12:49 p.m. Stephen Tompsett via time-nuts < time-nuts@lists.febo.com> wrote:

time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send an email to time-nuts-leave@lists.febo.com

Hi

I guess I’d add to that ….

If you head back into the early 1960’s indeed the terms for which end was which made sense. This end was your modem. That end was your Teletype machine. The idea that a computer would attach to this sort of stuff at the “user end” of things …. nope not part of the picture.

By the end of the 1960’s that had all changed. Like a lot of terms, they have hung around for quite a while. Roughly since about 1968, they have simply been a “pinout identifier”. Tying the to a pice of hardware based on rules …. not so much.

The pinout and nomenclature for the DB-25 was effectively “defined” (at least in the US) by Bell / Western Electric when they built up their stand alone “dial up" modems. The same was true for what we call RS-232 signaling (which replaced a current loop interface). As noted, just what that pinout was varied a bit depending on the model and purpose of the specific modem. It was quickly copied by a number of outfits. Eventually a “standard” version was defined and blessed by the appropriate standards organization(s). It was effectively a copy of one of the Bell implementations. Even with that, a lot of “non-standard” implementations came out here and there.

By the time DB-9’s came along, it was pretty obvious that the idea of a definition by a standards organization was not going to be very useful. They simply didn’t bother. That’s not to say that DB-9’s are any more or less standard than DB-25’s. They both have their quirks. With fewer pins to play with the DB-9 seems to have fewer odd derivatives.

Simple answer to any “hook it up” process is going to be to look at the pin definitions and start from there. If the software has documentation, it just might tell you what you can ignore. The further back you go the more likely it is that various odd pins will need to be taken care of. There is no “one size fits all” approach and hasn’t been for close to 60 years. In many cases folks “hack” the interface rather than wire it correctly. There are a lot of instruction manuals that tell you to do just that ….

Lots of fun.

Bob