Micrologix 1500 Modbus Chan 1 not able to connect

Hi Folks,


I have a Micrologix 1500 Series C rev 9 with a 1761-net-AIC connected to a weight transmitter. Communicating via Modbus RTU as Master.


Everything is working perfectly when connected to Channel 0 (I can use either PM02 or AM00 and both work fine). For hookup and HMI reasons, I need to get the Modbus connected to Channel 1, and I simply cannot figure out why it will not connect.


On the Logix500 side for CH1, I have the baud rate set matching the device (19200), The Driver set for Modbus RTU Master, No Handshaking, and I have only one simple MSG instruction running (on a 2 second timer) and it has the proper controller (Channel 1 Integral) and slave node address(2) set on both ends.
When trying to connect to the Micrologix, I've tried both a PM02 and a serial cable. I get one bleep on the TX of the AIC and thats it.


Anyone see anything missing?

Can you post a snap shot of channel 1's configuration?

and slave node address(2) set on both ends.

Click to expand...

"Set on both ends" ???

Sure, Here are a couple pics.


As far as node address on both ends, set on the weight module params as well as in the MSG setting.

Can you show us the whole rung with the timer used for the message instruction? And the whole rung of the message instruction?

It looks like you are getting data.

Mickey, the data in the screenshot was from when I was connected via chan 0...



*** UPDATE*** I hooked up the AIC to CH1 with a NULL cable and everything started working... Tough lesson learned on my end( Cant use a standard 232 for this).



I figured the PM02 would work from the round 8 pin on the AIC to CH0... Not the case! WTH



Hope this thread helps someone else out there!


Thanks Mickey.