GE RX3i CPE305 serial port configured as "RTU Slave", trying to find address info

[defcon.klaxon]

GE RX3i CPE305 serial port configured as "RTU Slave", trying to find address info

Hi guys,

I'm working on a system with a GE CPE305 and the serial port is set up as a "RTU Slave"; from reading the documentation, this means the port is, "Reserved for the exclusive use of the Modbus RTU Slave protocol". This port is connected to a Red Lion DSPLE data converter which is accessing the CPE305 as a MODBUS master. This DSPLE is connected to the internet, and the data is provided to an HMI in the client's office.

Looking for further information about how this port actually works, I've come up lacking. I am trying to find info about how this port is going to work for accessing the different register addresses. Basically I'm trying to figure out how various registers are "converted" for Modbus RTU when there doesn't seem to be any actual configuration going on in PME. So basically, how would I access %R registers versus %M or %I or %Q, if that makes sense. I'll keep searching but was hoping someone might be able to provide some insight. Even reading through the 305 manual, it doesn't seem to explicitly describe how this works.

 

[Steve Bailey]

In Proficy Machine Edition hardware configuration for the CPU module there is a setting for Modbus mapping.

 

[defcon.klaxon]

In Proficy Machine Edition hardware configuration for the CPU module there is a setting for Modbus mapping.

Hi Steve, I did indeed see that but I thought that was for Modbus TCP only. On my CPE305 module the table says "Modbus TCP Address Map". Because I'm using the Modbus RTU slave through the RJ25 connector, I didn't think that would be the right data but maybe I'm wrong? Checking now, all the data in the tables is greyed out and I can't adjust anything.

 

[Steve Bailey]

It would seem to me a massive waste of resources to have separate maps for Modbus RTU and Modbus TCP.

 

[defcon.klaxon]

It would seem to me a massive waste of resources to have separate maps for Modbus RTU and Modbus TCP.

I would agree, but then why would they specifically called Modbus TCP? Also, the mapping on that page doesn't seem to match what I've found in the system thus far.