Micrologix 1400: AWT instruction is not working in CH0

[asteroidehk]

Hello friends

I am trying to communicate a ML1400 with a production display. I need to send 2 bytes and I receive 32 bytes.

I have done this with a ML1500 (COM1=ASCII) a RS232/RS485 converter to the display. It works fine.

I need to do with a ML1400, because is the PLC that is in the plant, also it has RS232/RS485 combo port in CH0, so I could eliminate the RS232/RS485 converter. (ML1500 is the PLC that I could get first to do trials).

Now, I have a ML1400 to do trials. From the ML1500 working program, I have changed ML1500 to ML1400 in controller properties, channel 1 to channel 0.

But, AWT instruction is not writing. No error code is present.

I have done a test: using CH2 in ML1400, with identical parameters for CH0 and the converter, and it´s working in CH2¡¡¡ But, this Channel 2 has not RS485 option, so I can not eliminate the RS232/RS485 converter.


Why AWT instruction is not working in CH0?

What do you recommend?

Thanks in advance.