Rockwell Automation 1756-DH485 ControlLogix DH-485 Communication Module User Manual - Manual (Page 64)

Publication 1756-UM532A-EN-P - May 2006
6-4 Communicate Between SLC Controllers over DH+ and DH485 Networks
Configure the SLC 5/03 Controller Channel 1 Link ID
The SLC 5/03 remote link ID needs to be programmed to match the link IDs
configured into the 1756-DH485 module. These are labeled in the channel
configuration as the Channel 1 Passthru Link ID.