Honeywell HC900 User Manual

Diagnostics and Troubleshooting - User Interface 

Revision 5 

  HC900 Hybrid Controller Installation and User Guide 

125 

9/03  

Table 27 - Controller Module Diagnostics 

OI Screen 
Item  

OI Screen 
Item Value 

Number of 
LED 
Strobes  

Possible Cause 

Control File Action 

User Action 

IO RACK 

COMM FAIL 

6 

The Main CPU is 
unable to successfully 
communicate to an 
expansion rack(C50 
CPU only) that is in its 
configuration. 

1. Verify that the 

expansion rack 
should be in the 
configuration 

2. Verify that the 

jumpers on the 
scanner are set up 
for the correct rack 
address. 

3. Check that 

expansion rack is on. 

4. Check the expansion 

rack’s status LED for 
diagnostic 
information. 

5. Check that cable is 

connected to 
expansion rack. 

6. If a hub is used, 

check that all cables 
are properly 
connected to the 
hub, proper 
crossover cables are 
used, and that hub is 
powered. 

7. Cycle power to the 

rack. 

8. Cycle power to the 

hub. 

9. Replace the 

expansion rack’s 
power supply. 

10. Replace the 

expansion rack. 

11. Replace the 

expansion rack’s 
scanner board. 

12. Replace the main 

CPU. 

 RACK 

SW 

INCOMPATILITY 

6 

The Main CPU 
determined that its 
software is not 
compatible with the 
scanner module. 

All associated module 
diagnostics are set to 
MODULE NO COMM. 
 
Refer to MODULE NO 
COMM diagnostic for 
further details. 
 

1. Upgrade the scanner 

software either by 
replacing the module 
or doing a code-
download. 

2. Update Main CPU 

software either by 
replacing the module 
or doing a code 
download.