Incorrect characters on serial connection

[Jarosław Mazurkiewicz]

Altair-Duino 1.5 +  I/O expansion

TTGO VGA32  +  MAX3232

I have a cable for I/O expansion serial port connected to the RS-232 port on the MAX3232 and TTGO VGA32 and, unfortunately, the standard message to confirm the switch to a new connection type is displayed as in the image (also updating itself):



Jumpers on I/O expansion are set to 9600 8N1.

Do you have any idea / solution to the problem?

[Jarosław Mazurkiewicz]

Of course in Altair-Duino settings A6/A7 also set to 9600 8N1.

[Eightbitswide]

Can you post a couple of pics of your connections on both the MAX2323 connection and the TTGO VGA32?

8b

[fridtjof.ma...@gmail.com]

^N and ^O should shift character set (as far as I remember). SI and SO

It could well be that your "F12" or whatever generated a strange sequence including the control character that selected the character set.

Just a wild guess -- I do not know this terminal.

[Jarosław Mazurkiewicz]

None of the solutions helped - it is connected as in John's photo.

It prints out weird characters, but always the same - as in my photo.

[Jarosław Mazurkiewicz]

I do not own a tester.

Tx and Rx wires I swapped many times :)
I use this adapter:

niedziela, 13 listopada 2022 o 03:18:33 UTC+1 John Galt napisał(a):

you are using the null modem converter?

the leds on the 232 converter lit?

do you have a 232 diagnostic link tester?

when i had the issue of garbage it was a combination of  not using the null modem converter and having the TX and RX wires reversed.

[pat...@deltecent.com]

I've never known a null modem adapter to be the cause of garbled characters and as John pointed out, that is a gender changer, not a null modem adapter.

What causes garbled characters in an asynchronous serial transmission are either bad serial drivers or clocks (baud rate) that are out of sync. Incorrect wiring typically causes no data transfer at all.

It's also possible your serial connection is working fine and what you're seeing on the screen is what was actually sent by the transmitter, meaning the software is sending the wrong data or the problem is with the I/O expansion (has it been tested and is known to work?)

When pressing F12, it looks like a graphical configuration screen is supposed to be displayed where you configure the settings. Does that screen come up and can you send a picture of that? The video I watched on YouTube said that the TTL to RS-232 adapter has to be powered off when pressing F12 and configuring the device. I don't know why this is, but are you doing the same?

I think I may get one of these devices to mess with. Would you mind describing the exact steps you're going through; what is connected, what is powered on at what time, and what happens when you press F12?

On Sunday, November 13, 2022 at 5:54:58 AM UTC-8 John Galt wrote:

That’s a gender changer not a null modem adapter

https://www.amazon.com/Null-Modem-Adapter-Male-Pack/dp/B07GV5PGJ5

[pat...@deltecent.com]

It is not clear to me if the junk is showing up immediately when he presses F12, if F12 is working correctly and brings up the configuration screen and junk shows up when confirming the configuration, or if the junk shows up on the screen when he sends data from his Altair Pro.

If pressing F12 produces the junk, and he doesn't get the configuration screen, or the junk shows up without the Altair Pro even connected (or the RS232 converter powered on), then RS232 has nothing to do with this and I would suspect his terminal server is defective or was not programmed correctly.

I'm not sure how the electrons know the difference between a regular null modem adapter, robust null modem adapter, breakout box, swapped TX/RX pins, or straight/null cables. I'm not saying that's not your experience. I'd would like to know the "why" behind it.

On Sunday, November 13, 2022 at 8:20:37 AM UTC-8 John Galt wrote:

I had similar issues in the past with these 232 converters.

Many people think you can simply swap around the TX and RX lines and get a proper cross over but the 9 pin converter does not like that and you can get junk on the screen.

With the Altair Pro i have noticed everything needs a null modem converter to work correctly i spent time with a 232 tester to verify.

if you hit shift F12 you get the Terminal I/o card config and you can invert the 232 communication however it does not work with devices and you should leave it as default and use the null modem converter.

i have a serial switch connected to the serial port with a null modem converter on the main so i can share it with all devices.

Any junk that comes in on the serial line will show up as garbled text on the terminal. Flipping the TX and RX the wrong way produces it.

without the null modem converter and with the TX and RX connected correctly you will get nothing on the screen.

You can test the terminal outside of the Altair to make sure you have your wiring correct.

Take the VGA32 terminal and connect to to a pc or mac and using terminal software just connect to it at the 9600 baud you want.

you can use a 9pin serial to usb adapter in this case because the modern computer pc or mac is going to have a HOST usb.

Confirm you can type from the terminal to the modern computer and it will display and vice versa type from the modern computer to the VGA32.

that will confirm your terminal is working correctly then the issue is with the altair.

As i learned thanks to David about USB host and slave connections the Altair Pro usb ports are slaves so they won't work unless you have the VGA32 connected to a host usb board.

since we are dealing with serial the only thing left is a null modem converter.

once the null modem converter is between the Altair and the serial 232 converter connected into the VGA32 then you will get the text correctly on the screen.

there are all in one cables for male to male and null modem conversion that will simplify the number of converters you need.

 

[Walt Perko]

Hi, 

I wish there was a version of the ESP32 VT-100 board that used a USB Keyboard and Mouse and had a 3.3V Regulator and 6V-12V power input to be more convenient.  Although I have  some PS/2 keyboards, I have to get a PS/2 mouse if I can't find one in a box of old computer stuff.  

It seems to me to make more sense that these new emulators are designed for more modern connections too, not stop at early 90's tech. when making stuff for 70's tech.  

. 

[Jarosław Mazurkiewicz]

"Null modem adapter" also displays "gender changer " in Goole (hence the misunderstanding), but thanks for the information.

There are three variants of null modem adapters:

https://www.delock.com/infothek/Nullmodemkabel_RS-232/nullmodemkabel_e.html 

For now, I soldered the first variant and managed to connect to a Psion 5MX, on which I have Debian - It works (as VT52):

The settings screen looks like this:

Unfortunately, with Altair-Duino, it still doesn't work. I will continue the battle tomorrow :) 

[Eric Svedberg]

I have one of those small orange-labeled null-modem converters that looks like a gender changer.  I tested the connections from one side to the other and it matches with the Delock Null modem cable variant 1: The classic.

https://www.delock.com/infothek/Nullmodemkabel_RS-232/images/nullmodemkabel-variante1_grafik-3_870x280.jpg

It has the following connections:

1+6 - 4

2 - 3

3 - 2

4 - 1+6

5 - 5

7 - 8

8 - 7

eric

On Sunday, November 13, 2022 at 7:30:17 PM UTC-6 John Galt wrote:

oh also if you see my thread this past week

https://groups.google.com/g/altair-duino/c/VNEDSyn7Jns

i took some pictures as i was figuring out the wiring and in one you can see the Gibberish on my VGA32 before i got it sorted.

On Sunday, November 13, 2022 at 8:25:47 PM UTC-5 John Galt wrote:

now you know the terminal works.

here are some things i noticed when my wiring was wrong because i was figuring out the silk screen was incorrect.

i was moving my ground around and the mouse stopped responding. 

playing around with the 3.3V suddenly my keyboard stopped responding.

messing around with the TX and RX on various pins resulted in things locking up not responding.

when i figured out the wiring then it was working, at one point i even blanked my Altair PRO as i killed the firmware on the DUE and had to reload.

at this point the wiring is right. Your keyboard is working so you know the VGA32 is doing what its suppose to.

On to what is up with the Altair.

The reason i have experience with the Terminal I/O weirdness is because over a year ago now i wanted to connect my OKIDATA 192 parallel printer to my Altair pro Port B(9 pin serial).

Thus began this crazy quest where I converted the printer to serial communication but that didn't work because of the missing voltages and low voltages the Altair Terminal I/o used.

I had to wire in a self powered B&B Serial to parallel converter, then i had to play around with different types of null modem connectors and patch cables using my 232 tester and figure out a combination that works.

took many failures to figure things out. the printer and CP/M don't 100% like each other i think because Cp/M does not check if the printer is ready to receive and thus it drops characters if i dump too much information to the printer.

but if i use Word star 4 with okidata support then its amazing i get all the full functions and the printer drops nothing so i output my source code through wordstar 4 to the printer.

All my attached serial devices to the altair use null modem converters.

I have my Okidata printer, a WIFI modem, A speech sound device, the VGA32. I have 2x 9 pin serial ports the second comes in with the TXL/RXL mod for the DUE, and 2 USB connections to the native and programming ports on the DUE.

basically my machine is REALLY loaded and i have a serial switcher. the VGA32 is on the TXL/RXL which is dedicated just for the new primary terminal (VGA32)

i also have a 1980s Motor Dyno and Battery Cycler that i have hooked to the Altair again they needed null modem converters to work.