Page 11 of 60 
 
 
1.1.2.3.1   Class ‘A’ Abnormal 
 
Description: 
 
The addressable loop or RUI Bus has an open circuit. 
 
Possible causes: 
 
  Open circuit in the wiring loop 
  Bad connection at addressable point (on addressable loop faults).  
  Bad connection at remote transponder or LCD Annunciator (for RUI Bus faults) 
  Faulty addressable loop or RUI card 
-  Check this fault by „looping out‟ the A and B terminals on the RUI/Mapnet/IDNet card to clear 
the fault. If fault does not clear then card may be faulty 
 
1.1.2.3.2  Channel Failure Abnormal 
 
Description: 
 
The Loop card cannot communicate with any device on the loop. Be aware all devices associated with this 
loop will indicate a „Normal‟ state to prevent multiple faults per display. 
 
Possible causes: 
 
  The Loop has a Short circuit 
  The Loop has an Earth fault 
  The Loop is not connected or incorrectly connected 
 
1.1.2.3.3  Channel Initialization Abnormal 
 
Description: 
 
This fault typically occurs at startup with IDNet loops and will normally clear after a couple of minutes if a lot 
of Isolators are fitted.  
 
Possible causes: 
 
  If the fault continually re-appears the loop length maybe too long or too noisy  – Contact your local 
Simplex® branch for assistance 
  Possible bad device causing communication errors 
-  Disconnect devices at half way points until the fault clears to locate the faulty device