Mercury controller has difficulty establishing communication with an OSDP reader

 

This is an important notice for users deploying Mercury Series 3 MR50, Series 3 MR52 as well as LP1501, LP1502 and LP4502 Intelligent Controllers.

 

The Mercury controller(s) may have difficulty establishing communication with an OSDP reader.

 

In certain installation environments, OSDP readers are interpreting a non-driven 485-line as data. This interpretation results in a communication fault that is inhibiting the panel and reader from properly communicating.

 

 

Place a 1K ohm resistor to pull down the Mercury TR- to 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. Please ensure that the DC Ground (power supply return) is not connected to earth ground.