Loop (Line) Monitoring of Digital Input


#1

I am using Honeywell Safety System. I am doing loop testing of Digital Input, DI has loop monitoring function.

So how will i can test the loop monitoring function at Factory.

Any suggestion is welcome.


#2

I have 1 k and 10 k resister with me but i don’t know how to use this.


#3

Case : your Digital Input in monitoring function. you can check at the safety builder software, if the DI faulty it means your line monitoring bad/problem.
use this -------R(1kOhm)--------------------------------------------------I
------------------------------------ I ----------------------------------------- I
------------------------------------ I------------------------------------------ I
-------------------------------R(10kOhm) ---------------------- SWITCH(LS/PS,etc)
--------------------------------------I---------------------------------------- I
--------------------------------------I---------------------------------------- I
---------------------------------------------------------------------------------I

If the DI module detect 1 kΩ, it means the system in close loop mode ( in safety system usually this is the normal mode)
If the DI module detect 10 kΩ, it means the system in open loop mode ( in safety system usually this is the trip mode)
but if the DI module detect the resistan more than 10 kΩ or megaOhm or ∞, it means something wrong with the cable or grounding or etc