... %low bat voltage function this door contact is suitable for our 2200,2300,2300G, 2300C, 5900, 5800, 5700, 5100 etc. when ... bat battery, this door contact will send this signal to our host machine, then, the host machine will show and alarm ... tests the low bat battery and be used with our host machine together. Host machine reminds the user to replace its battery ...