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I/O Module Diagnostics and I/O Calibration
Number of
Fai l u re
Descri p tion
Shift Register
The loopback test of the shift
register failed.
Bad channel details
Below is a list of conditions that can cause a BAD CHANNEL I/O module diagnostic.
I/O Summary Error Status
Bad Channel
Burnout Fail
Convert Fail
No Channel
Over Current
Revision 9
May 2014
Contact AC DC Relay AC DC

Table 24 Bad Channel details

If the channel is an Analog Output: There is no
physical output device connected to this
channel, or the output device is showing an
open connection.
If the channel is a Pulse Output: The channel is
failing to output the correct value.
A BAD CHANNEL I/O module diagnostic is
The sensor – T/C, RTD, or mV source -- is
failing burnout checks. A BAD CHANNEL I/O
module diagnostic is posted.
When attempting to take a reading, the analog-
to-digital (ADC) fails. This can occur if the
incoming signal is either too large or too 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. A BAD
CHANNEL I/O module diagnostic is posted.
There is no hardware on the I/O module to
support this channel. For example, the
customer configured Channel #15 for a given
module, but there is an 8-channel module
installed in the rack. A BAD CHANNEL I/O
module diagnostic is posted.
A Digital Output module detected an excessive
amount of current on its output terminals. Note
that this message will only appear for the 32-
channel DO module. A BAD CHANNEL module
diagnostic is posted.
900 Control Station User Guide
PFQ User Action
Replace module
Check terminal block
Replace module.
Check terminal block connections
Replace source element
Replace module.
Check the signal level being
applied to the terminals.
Replace module.
Main Menu
What to do


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