TB 18.5 – Series 3 Boards and LX Controllers communicating with OSDP readers

Topic:  Series 3 Boards and LX controllers may be impacted when communicating with OSDP readers

Applies to: Series 3 Mercury boards and SSP-LX controllers communicating with OSDP readers

Summary: 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 the series 3 boards or LX controllers, place a 1K ohm(Ω) 1% resistor between DAT D0 and GND line.  This will create a communication bias that will keep the reader from improperly interpreting data. To function properly, there must be NO ground faults in the installation.

Download Technical Bulletin (PDF): 

  TB18-5 (271 KB)