TB 18.12 – Mercury EP/LP Controllers and issue communicating with OSDP readers

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Topic:Series 2 and Series 3 controllers/sub-controllers may have issues communicating with OSDP readers

Applies to: Mercury Series 2 boards (NSC-100, SSP-D2) and Series 3 boards, including the SSP-LX (LP-4502) when communicating with OSDP readers.

Summary: The OSDP readers are interpreting a non-driven 485-line as data in certain installation environments. This interpretation results in a communication fault that will inhibit the panel and reader from properly communicating.

Resolution: For users deploying series 2 or series 3 boards that are communicating to OSDP readers, place a 1K ohm(Ω) 1% resistor between DAT D0 and GND line.  Download tech bulletin below for images.

Download Technical Bulletin (PDF): 

  TB 18-12 (151 KB)