slc 5/05 -> slc 5/05 communication using chan0 rs232

basically what the title says

im trying to transmit data from one slc to another via the chan0 port.. i have chan0 in USER mode on both plc's, same COMM settings (baud,etc), and i am using a generic serial cable. i dont get any errors (i did initially when i was not in USER mode), but i also dont find another on the line using ABL instruction on the receiving PLC. this should work correct? before i tear my hair out looking for a sanity check.. do i need to null modem anything?

thanks as always

Why are you messing with serial? With the SLC5/05 you have ethernet...

working on a project which is going to take data over the serial port from a device

dont have the device, but do have another plc. just looking to simulate the data.

Yes, you need a null-modem cable.

Yes, with 02 PLCs you need a null modem cable , because PLC are DCE, Data Computer Equipment, and they have their's own modem built in.

If you plan to use later a PLC and another piece of equipment, you should check if it's a DCE or DTE, Data Terminal Equipment. If it's a DTE you have to use a modem serial cable.

OK, so i tried messing with this again this morning. as a baseline i used a device i have lots of experience with using and a ML1100, which i also have a good bit of experience with. the device communicates with the ML1100 right away but i cant get anything across to the SLC.

one thought i had, do i need to use the AB cable to use the rs232 port of the SLC unit or will any generic serial cable work?

on top of that it has to be something in my ladder logic or in my controller config. is there anything glaring that makes this sort of operation different between a SLC and a micrologix? any sample ladder logic that might be able to get me on the right track?

thanks again for all your help so far, forum-ers

So.... which cable are you using? Straight or Null modem?

Can you post your code, just the message setup and channel configurations will do.

as far as cables go

i have tried the AB slc cable straight and a generic serial cable both straight and with a null modem attached

channel info

GENERAL
Channel 1 Write Protected: No
Channel 1 Edit Resource/Owner Timeout: 60
Channel 1 Passthru Link ID: 2
Channel 1 Diagnostic File: 0
Channel 0 Write Protected: No
Channel 0 Edit Resource/Owner Timeout: 60
Channel 0 Passthru Link ID: 1
Channel 0 Current Mode: User
Channel 0 Mode Change Enabled: No
Channel 0 Mode Change Attention Character: \1b
Channel 0 Mode Change System Character: S
Channel 0 Mode Change User Character: U
Channel 0 Diagnostic File: 0

CHANNEL 0 (USER) - Driver: ASCII
Baud: 38.4K
Parity: NONE
Stop Bits: 1
Data Bits: 8
Control Line : No Handshaking
Delete mode: Ignore
Echo: No
XON/XOFF: No
Termination Character 1: \d
Termination Character 2: \ff
Append Character 1: \d
Append Character 2: \a

here is a description in psuedocode of my ladder logic just to test for data received

(timer rolling ever .01 sec)
xic TIMER.DN to call ABL (chan 0) using control R6:0 AND reset timer

xic R6:0.FD AND xio response_not_received, ARL chan 0 using control R6:1 into ST10:0 and latch response_not_received so it doesnt trample on the response

hopefully this makes sense and is sufficient!

It's easy enough to make your own serial cable, just measure from ground to pin 2, pin 3. The one with voltage is TX, you wire that to RX on the other device. Do the same for any other pairs.
Use a laptop with serial interface to monitor the communications, you can wire Rx in parallel (not TX)
Tip - start off at a low baud rate it's more forgiving. Once you see the data is getting through correctly then you can speed up.
Roy