5.2.2 Device addressing, Class A, Class B, and Class X
The IDNet section can be wired as a Class A, Class B, or Class X circuit.
Class A wiring: Class A wiring provides an alternate communication path that maintains communication to all devices when a single open
circuit fault occurs. Class A wiring requires two wires to be routed from the IDNet Primary Terminals (B+, B-) to each device, and then back
to the IDNet Secondary Terminals (A+, A-). Wiring is in/out, and T-tapping is not permitted.
Class B wiring: T-tapping is permitted on Class B wiring. IDNet wiring is inherently supervised due to individual device level
communications. EOL resistors are not required.
Class X wiring: Class X wiring provides an alternate communication path that maintains communication to all devices when a single open-
circuit fault occurs. Class X also wiring provides resilience when a single short circuit fault occurs.
Note: Class X wiring requires the use of IDNet isolator devices.
• If there are no remote isolators or isolator bases on the loops, device addressing can be assigned without concern for sequence.
• If there are remote isolators or isolator bases on the loops, the required addressing approach is to start from the B side and assign
each successive isolator a higher address than the isolator it precedes.
• For Class B wiring only, the A output and B output on a loop are connected in parallel using a jumper.
page 23 579-1102AR Rev C
Z-20 Agent Releasing Panel Installation Manual
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