Reader LED on 2220 IDRC Reader 2 flashes red / green / red / green on idle


The Reader LED on an LNL-2220 IDRC Reader 2 flashes red/green on idle.
This issue can occur after upgrading OnGuard and it is only seen on the Reader 2 port of the LNL-2220.
Prior to this happening, the LED on the reader is solid red, but then changes to a red/green flashing pattern.


There are two options:
  • Option 1: Add a pull up resistor from the LED output (LED) on the LNL-2220 to the reader power supply (VO).  The value of this pull up resistor can range from 1K ohm to 10K ohm.
  • Option 2: Add the following lines to the ACS.ini file on the Communication Server machine and then Restart the Communication Server.

This issue is caused by invalid TTL values that the reader is sending to the LNL-2220 panel. Typically, the LNL-2220 can handle the invalidTTL values, but in some cases component variations (for example, internal capacitance, voltage drop, threshold knees, leakage current, etc) do not allow the LNL-2220 to handle the invalid TTL values.
Unfortunately, there is no way identify which reader port may cause a problem or which LNL-2220 may experience this issue.

Applies To

OnGuard (All versions) 

Additional Information

For more information on customizing Reader LED modes, see KB Article 1289 (