AB7642 Communication issues

Hi There,

I have a customer using the AB7642 and they are having issues getting it to work right now. I will quickly go over the architecture below.

The Anybus Gateway is going to be between an older Modicon PLC that will be a Modbus plus slave, and on the other side their main AB PLC communicating via a prosoft Modbus TCP card that will be the Master.

Can you please confirm if the gateway will work in this scenario, and if you could provide some details on how to accomplish this, that would be great. Thank you very much.

Hi Sean,

Just to clarify, the Modicon PLC is acting as a modbus plus slave or as a modbus plus master in this setup?

As a modbus plus slave, thanks!

Hi Sean,

This should be possible. I would have them check their Node settings on the gateway. this document should help with the communication setup for the modbus plus side.

Here is also the document page on teh x-gateway with contains an application note on the setup.


Thanks Zach.

Hi Jeff,

Please see the response from HMS below. I hope this helps you out. If not, it may be best to reply to Zach as he can help you out better than I will be able to. Thanks Jeff.


Thanks Sean. I had a quick look in the manual you sent. I am concerned about the below statement. It indicates it cannot initiate commands (if I’m reading this correctly). I will have to try and get in touch with Zach.

About the Modbus Plus Slave Interface
The Modbus Plus Slave interface acts as a host device. A host device can be read and written to from another Modbus Plus host device or controller. The Slave interface will not initiate any point-to-point communication to other nodes, it will only respond to incoming commands. It can, however, broadcast Global Data to other nodes on the network, and extract Global Data from another node.

Hi Sean,

The device we have only acts as a slave on the Modbus Plus network which is why it does not initiate point-to-point communication with another node. Since the PLC is also a slave device you will have to use Global data for communication.