Honeywell HC900 User Manual

Diagnostics and Troubleshooting - User Interface 

130 

  HC900 Hybrid Controller Installation and User Guide 

Revision 5 

  

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 

RS-232 GOOD  N/A  N/A 

N/A 

N/A 

 DATA 

LINK 

FAILURE 

8 

A large number of 
messages are 
resulting in data link 
errors. 

1. Rack 1 monitor block’s 

COMPORT DIAG is set 
to FAILED. 

2. Rack 1 monitor block’s 

RACK OK pin is turned 
off. 

3. ASYS block’s HW OK 

pin is turned off. 

4. If configured as a 

Modbus master:  
1.  ASYS and FSYS 

blocks’ Modbus Master 
Fail pins are turned on. 

2.  Slave and read blocks 

associated with the 
slaves experiencing the 
failure have their read 
pins frozen to the last 
value read. 

3.  Slave blocks associated 

with the slaves 
experiencing the failure 
have their BAD COMM 
and NO SCAN pins 
turned on. 

4.  IN SCAN STATUS is 

set to NO for all slaves 
experiencing the failure. 

5.  COMM STATUS is set 

to BAD for all slaves 
experiencing the failure. 

6.  The slaves with the data 

link errors have a non-
zero data link error 
count. 

7. The slaves experiencing 

the failure are moved to 
the background scan 
rate.

 

1. Check baud rate 
2. Check connectors 
3. Check cable polarity 
4. Isolate cabling from 

electrical 
interference 

5. If RS232 to RS485 

converter is used, 
check its power, 
switch/jumper 
settings, and polarity. 

6. If configured as a 

Modbus master, use 
the slave status 
screens to determine 
which slaves are 
experiencing the 
problem. For those 
slaves check: 
• power 
• connections 
• address 
• baud rate 
• parity 
• number of stop bits 
• for electrical 
interference 
• grounding 
• termination resistor (if 
at end of link) 

7. The diagnostic is 

cleared by clearing 
the port’s statistics.