[Modbus comms between Schneider and allen Bradley]

kaiser_will - I am actually only trying to write one value to the Receiving PLC. Ive tried sending an array of 20 words to allow for other values to be added easily later but next time I am on site will reduce this and see if I can make a difference.

[Modbus comms between Schneider and allen Bradley]

kaiser_will, thanks for the reply. I had to index the registers one down in order to get them to read. Ive tried several attempts at doing the same for writing and no joy... any other possible suggestions???

[Modbus comms between Schneider and allen Bradley]

Hi all,

 

currently as part of a project I am trying to communicate between a Schneider M340 plc and an Allen Bradley micrologix processor. I am programming the M340 and the micrologix has been installed by another supplier. they have mapped the Modbus registers on their side and given me a spreadsheet with these. 

I am able to read values with no issue but I cannot write values back.   i've included a screenshot or the read_var and write_var instructions I am using.

I would really appreciate any help if anyone has any insight on this

 

Mark