ALC DIAG485 ARC156 CMnet diagnostic board. A DIAG485 is a diagnostic board that shows the communication signal levels on a network segment. Add at least one DIAG485 to each network segment.

A DIAG485 located near the center of the network segment can also add bias to reduce the effects of noise on the network. You must put this DIAG485's Bias jumper in place. Only one DIAG485 per network segment can have its Bias jumper in place.

NOTE

If you are using BT485's, you can still use one or more DIAG485's for diagnostic purposes, but you must remove their Bias jumpers.