RS-232 Woes? Serial Coms setup and troubleshooting for your vintage gear.

Рет қаралды 1,985

Күн бұрын

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In this video we take a look why ‘simple RS-232 communications are not always so simple. We’ll learn a bit about what RS-232 is, figure out how to properly wire two devices together and about tools that can help in this regard. We also learn how to configure the communication parameters and how to figure out why things aren’t working with your hardware and/or software.
Timeline:
00:00 - Welcome
01:14 - Introduction to RS-232
05:28 - Wiring, connectors and tools.
16:05 - Example #1, DB9 to DB25 adapter
19:36 - Example #2, CGP-115 cable
35:05 - Example #3, EOL handshaking, wrap up, thanks!
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Пікірлер: 27

@chrisfezzler2878 6 ай бұрын

Hey Birt! Serial KIller! (Someone had to go there.)

@robbyxp1 6 ай бұрын

Serial Comms is still alive. In my Aero industry, Arinc 429 (serial) is very much alive. Inside our satcom board, we use serial to connect major bits together. It has many advantages over using Ethernet/USB etc. its simpler, most chips have at least 1 UART, and less susceptible to hacking.

@geoffcollins6601 6 ай бұрын

I have had to work with many different serial standards for control and computer systems. RS232 hand shaking signals were the bane of my existence on some days, often a null modem wasn’t enough for reliable comms. Thanks for an awesome trip down memory lane.

@HeyBirt 6 ай бұрын

Indeed, for something supposedly so simple it can sure be a chore to get two things talking.

@dipdoting 6 ай бұрын

Very timely, Birt! I just picked up DB25 cable for my TRS-80 Model II. In the old days I'd just find another device with an RS232 port and get things going, but this is going to be trickier hooking it up with my 2020 Mac M1. Your video helped a lot, thank you!

@jensschroder8214 6 ай бұрын

For the Comodore AMIGA, 5 to 15 V was enough for low and 0 to minus something for high on the serial port. This means that the serial port could be operated with an inverted TTL signal as well as with a correct RS232 communication. For the output there was correct +/- 12V. With a transistor and a few resistors it became TTL again.

@Gringo_In_Chile 6 ай бұрын

I have a similar reference book, called "Pocket Ref" By Thomas J. Glover (don't know what happened to Millie M. Young. 4th edition 1989-2012. Mine is more of general reference book. Everything from rope knots to first-aid to the connector pin-outs (like your RS-232 example).

@davidlarson4164 6 ай бұрын

I work for a major telco and part of my job duties is installing and turning up the customer e-mux (hand off equipment) for business fiber. Guess what we use to load the scripts, provision and turn them up? PuTTY and RS-232

@tenminutetokyo2643 6 ай бұрын

Happy new year!

@derekchristenson5711 6 ай бұрын

Ooof, yeah, these issues are all too familiar! Trying to get computer X and computer Y to exchange data using "the same protocol", wasting infuriating amounts of time to figure out that one needs two stop bits or only works at 2400 baud despite "officially" supporting 9600, one requiring hardware handshaking and the other requiring software handshaking... Oh, not to forget the "RS-232C" cable that, for no good reason, didn't bother to connect anything but TX, RX, and GND despite having 25 pins... I'm glad I only need to get this stuff working for my hobby and not my job! Really, having only used RS-232C serial occasionally back when it was "current tech" for printers and occasional data transfer, and now using it more than ever before to play with my vintage computer collection (which, somehow, is almost entirely younger than me... hmmm... must be a math error there), I have wondered lately if all of this was simpler for the pros who DID have to configure, program, and use it on a daily basis, due to familiarity. But, thinking now about the existence of dedicated serial diagnostic machines makes me think that even the grey-bearded pros must have spent some infuriating hours trying to get this "standard" to work!

@iz8dwf 6 ай бұрын

great video Jeff!

@Mike_Neukam 6 ай бұрын

One of the more annoying things about UARTs is that most of them will control outgoing data flow in hardware (CTS/DSR), but I haven't found one yet that will assert RTS or DTR except under direct software control.

@user-nd8zh3ir7v 6 ай бұрын

very helpful thank you!

@konturgestalter 6 ай бұрын

fantastic

@BahamasRunner 6 ай бұрын

Hi, if you are into serious serial debugging (like me) you need either a HP 4951C, or a HP 4952A, and a HP 18179A pod. Or even better a HP 4957A. But beware of exploding caps when you get one of those. Edit: oh, you mentioned one of those briefly. But you can get them relatively cheap at "the bay" nowadays. Thanks for all your cool content! Runner

@HeyBirt 6 ай бұрын

Yes, the HP stuff is nice kit. I did manage to get by with my cheap LA and a level shifter on this occasion.

@N1UGK 6 ай бұрын

Hey Birt! I ran into exactly the same CTS issue connecting the PC-2 to the TP-10 thermal printer. I ended up with a similar “fix”.

@HeyBirt 6 ай бұрын

It was kind of an interesting problem. Don't know if I have run across it before. For slow devices like our printers it is a killer.

@iz8dwf 6 ай бұрын

whatever computer is show at 04:21, it has one of my handmade 8K modules in it :D

@HeyBirt 6 ай бұрын

That is a TRS-80 Model 100 someone sent me for repair. It has a test harness on it which automates testing of the system. I did not know you made those memory modules, nice!

@kevinmarr7094 6 ай бұрын

USB so much better than rs-232! I had to have so much gear to diagnose and adapt serial ports between devices.

@Raketenclub 6 ай бұрын

i have a model 100 thats behaving very weird on serial. my other 2 works. someone added modwires.... but i couldnt dig into it yet.

@sebastian19745 6 ай бұрын

Some old 8bit computers and even the PC running dos (the ctty command) could be used to accept console input/output from a terminal. Does that Sharp can be used with a terminal over the serial port? Just curiosity.

@HeyBirt 6 ай бұрын

Yes, the Sharp CE-158 ROM includes a SETDEV command which lets you redirect KB input to be from the COM port and LCD output (text) to go to the COM port.

@sebastian19745 6 ай бұрын

@@HeyBirt Thank you.

@greenaum 6 ай бұрын

"Zed" 88! not "Zee"! We are British, you know. At least 50% of RS-232 connections required a soldering iron anyway, back in the day, nobody followed any standards, they didn't even stick to the ones they'd made up previously!

@HeyBirt 4 ай бұрын

The British are determined to ruin English like the Italians did Latin. Just kidding of course. Years ago, I heard a joke which was something about how Italians ruined Latin, but I can't remember it or who told it. It did strike me as an interesting subject of humor though.