Prosoft EIP to Modbus TCP Gateway

Hello!

I need to communicate from a CompactLogix to a Unity based PLC via modbus tcp. I have a PLX32-EIP-MBTCP gateway configured to the point where both PLCs are attached and can see the gateway.

I have the EDS file for the gateway and was able to set it up in my ethernet tree in Logix. It appears to be configured correctly and connects just fine.

My questions comes down to mapping. I'm not sure which bits to use for the In/Outputs. Also, do I have to do anything in the gateway to make sure the translation pulls through correctly or for simple bit to bit communication is it pretty well plug and play (after setting the IPs).

Thanks!

I'm not quite understanding your question. Perhaps you can be a bit more specific.

ProSoft phone support is excellant, btw.

Looks like you are taking data on a one-way path from Logix to Modbus. In such cases, there's a few way to do it. The Gateway has its own data registers. To get data from the Logix to the gateway you can either set up commands in the Gateway (Gateway as Client) or Write to the Gateway from PLC (Gateway as Server). The gateway's internal database are all 16 bit registers so it's up to the PLC to interpret them in the right way.

On the modbus side, it's the same, you decided if you want the gateway to be the master or slave. If you want the gateway to be the master than you need to setup modbus command list in it.

Anytime you work with protocol gateway, it's a very good idea to map out the points using a spreadsheet that also document the data-path and Server(Slave)-Client(Master) relationship.

Ok, it sounds like this might be pretty simple then. I have the gateway configured with 248 Integers for Inputs and 248 Integers for Outputs in the Logix program. I was planning to write directly to aliased tags (ie Modbus_Gateway:O1.Data[0].0). If I do it this way, will it be as simple as finding the [0].0 input on the Unity side or do I need to set up some form of translation in the gateway itself?


Thanks for the help!!

Ok, so for the EIP side of things, you are using the gateway as the server(slave). Which is the way I would do it too.

You need to do a few things in the gateway with Prosoft Configuration Builder:

In the gateway configuration, under the EIP Server section, set the file size (16bit interger)to large enough to hold the data. The data should show up in the internal database somewhere between 0 and 3999. You need to check the manual to be sure.

On the modbus side, sounds like you like to do the same, that is, using gateway as the server(slave) then you need to set up the modbus database in the MPTCP Server to tell the gateway which section of the internal database are the Output, Input, and Holding register are located and make sure there are no overlap. This is why you need to use a spreadsheet to help you out.

It's not necessary for the data from both side to go to the same location in the internal database. You can use the "CommonNet" area of the PCB to move data around in the internal database.

I'll give this a shot. Thank you so much for the help. This definitely clears things up for me!