Diagnostics and Troubleshooting - User Interface
134 HC900 Hybrid Controller Installation and User Guide Revision 5
9/03
Bad I/O Channel Diagnostics
Below is a list of conditions that can cause a bad channel diagnostic. The associated function block’s I/O
status will indicate the nature of the diagnostic described in the failure column.
Table 29 - Bad Channel Diagnostics
Module
Type
Failure Description User Action
Burnout Failure
The sensor – T/C, RTD, or mV source --
is failing burnout checks.
1. Check terminal block
connections
2. Replace source
element
3. Replace card.
Under range
The signal at the terminals is less than
10% below the range of the sensor.
1. Check the signal level
being applied to the
terminals.
2. Replace card.
Over range
The signal at the terminals is more than
10% over the range of the sensor.
1. Check the signal level
being applied to the
terminals.
2. Replace card.
AI
Failing to
convert
When attempting to take a reading, the
ADC fails. This could result if the
incoming signal is either too large or
small. It also could result if the ADC
circuit is failing. If the problem is the ADC
circuit, most likely other channels will
have the same failure.
1. Check the signal level
being applied to the
terminals.
2. Replace card.
AO
Channel
Failure
The board indicates that the channel is
failing to output the correct value.
1. Check terminal
connections.
2. Replace module.
