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This section describes how the IDNet on the SPS connects to addressable
devices/detectors.
The guidelines governing IDNet wiring guidelines are covered in chpt 8, IDNet
Installation.
Up to 250 IDNet initiating devices are supported on the SPS IDNet channel. The SPS
supports both Class A (loop) and Class B(string) wiring. Class A wiring is mandatory for
connection to more than 40 devices.
Class A wiring allows IDNet appliances to communicate with the SPS even in the event
of an open circuit somewhere in the loop. Class A wiring requires that two wires are
routed from the SPS to each IDNet appliance, and then back again to the SPS.
Class B wiring allows “T” tapping, and therefore requires less wiring distance per
installation than Class A. Note that Class B wiring does not require end-of-line resistors,
because each IDNet appliance communicates directly to the SPS.
Ferrite beads are required on the SPS IDNet cables (ref Fig 7.1). Refer to chpt 8
IDNet Installation for the guidelines governing IDNet wiring.
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SPS IDNet Wiring
Overview
IDNet Wiring
Guidelines