Controllogix-Ethernet to Controllogix-Serial bridge with IAP

I have 2 controllogix processors. One is the master and polls info from 3 units over ethernet. The new (L61)unit is situated in a location where serial had to be used to connect to it. I have an IAP installed between the switch and the Serial connection to the L61. I can go online with the remote processor with RS Linx over the serial connection, but when I try to go through the IAP, I sense it for a moment, then lose it. When I try to MSG with a CIP, the MSG times out. Am I missing something in the configuration?
I can’t seem to find any docs pertaining to the configuration of slaving a Controllogix processor to another.

The problem is that ControlLogix speaks 2 protocols on the serial port.

  1. C*Logix speaks a normal DF1 like a MicroLogix or SLC5, but then you have to use the PCCC files in the RSLogix5000 program - these messages cannot access named tags directly.
  2. or C*Logix speaks a non-published proprietary “extension” to DF1 which encapsulates CIP packets.

The DOIAP cannot convert CIP-in-Ethernet/IP to CIP-in-DF1. It can only convert PCCC-in-Ethernet/IP to DF1.

So the only way this can work is if you treat the 2nd PLC as if it were a SLC5/05. You’ll need to create the RSLogix 5000 PCCC files, and then use the SLC5 type messages in the MSG block. This way the request to (for example) read 10 words from N7 creates a SLC5 typed read to N7, which the DOIAP unwraps from Ethernet/IP and creates a pure DF1 request into the serial-L61.

If you really require the CIP-in-DF1, then the Allen-Bradley 1761-NET-ENI is the only Ethernet-to-Serial device I know of which does support this special serial protocol.