Rockwell Automation 1756-DH485 ControlLogix DH-485 Communication Module User Manual - Manual (Page 65)

Publication 1756-UM532A-EN-P - May 2006
Communicate Between SLC Controllers over DH+ and DH485 Networks 6-5
Configure the SLC 5/04 Channel 1 Link ID
The SLC 5/04 controller 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.