Allen Bradley PLC 5 rs232 ascii communication

Hi, i need your help with rs232 communication. On the table i have PLC-5/30 (1785-L30B) and pc (in the future i want make little app - like scada). I want to send strings to the terminal on pc. When i'm using AWA or AWT i have 'ER'. This is my first time with rs232 on AB, have you some advice how make this connection. Down is screen from configuration.

Connection: Channel 0 ->rs232-usb cable -> pc (RealmTerm terminal)
CPU is configured for rs232C

just some quick ideas to try:

set the Channel 0 Communication Mode to "User" ...

try setting the String Length to 0 ... this tells the processor to send the ENTIRE string ...

watch the "COMM" LED on the front of the processor while trying to send/write the string ... it should flicker when the processor is transmitting ...

note that the ASCII instructions need to be "toggled/triggered" back and forth from FALSE to TRUE in order to transmit repeatedly ... specifically, just leaving the XIC instructions on those rungs TRUE all the time will only give you ONE transmission - not a repeating stream ...

since you have the Channel 0 set up for "No Handshaking" then you probably don't need the AHL instruction in your program ...

make sure that the terminal program running on the computer/PC has the same settings (baud, etc.) as the PLC Channel 0 port ...

BIG QUESTION:

how are you communicating with the PLC processor to program it while you are trying to get this working? ... if you're trying to PROGRAM through the same Channel 0 port that you're trying to use for the ASCII stuff – then you're probably not going to get this working ...

suggestion:

post your ENTIRE program file (RSP extension) as an attachment to this thread ... sometimes that can give us extra information to help with your project ...

In online i'm using dh+ from channel 1A - cable 1784-u2dhp
Now i'm trying send regulary message but noting happend (the LED doesn blinking)


my full program and screenshoot
Thanks.

see if the attached helps get you going with the basic ideas ...

I used a "quick and dirty" arrangement to "trigger" the AWT instruction - so that you could concentrate on the COMMUNCATIONS piece of the puzzle ... you can work on the logic piece later - after you get the communications working ...

note from from my earlier post ...

set the Channel 0 Communication Mode to "User" ...

Click to expand...

you didn't do that ...

also the Source for the AWT Instruction needs to be an ST-type data (String) ... I typed "HELLO WORLD " into that location as a test ...

leaving the String Length setting at 0 (Zero) tells the AWT to send the ENTIRE string ...

I set this up to write to HyperTerminal through the serial port of a PLC-5 once each second - and got it working as shown by the "HELLO WORLD" text in the screen shot ...
.