Redundant Configuration - Honeywell Series 8 I/O User Manual

6. Series 8 I/O Configuration
6.12. Electronic Short-Circuit Protection (Digital Output 24VDConly)

Soft Failure 180 - Output Short Circuit Detected

The output unpowered

The channel in Manual mode

Redundant Configuration

The firmware in a Primary IOM of a redundant pair notices the output miscompare and
signals the Secondary IOM to assume the role of the Primary IOM (assuming the
Secondary is synced).
The most common cause for the Digital Output over-current is a failure in the field.
There is a minor probability that the IOM itself might be the cause of the problem. Given
this, it is a common behavior for Series 8 IOMs to always switchover in an attempt to
localize the fault.
TIP
Note that the Primary switchover in most cases is done before actually
experiencing the over current condition.
If the cause for the Digital Output over-current is a failure in the field, then the new
Primary checks the same output miscompare problem, and react like a non-redundant
module. It performs the following:

Detects the output miscompare generate Soft Failure 23 - Failure in OP circuit/field
wiring detected by Analog Output/Digital Output.

Detects the over current and generate Soft Failure 180 - Output Short Circuit
Detected.

Sets the output to unpowered.

Sheds Mode to Manual control.

Sheds ModeAttr to Operator.
You should expect to see:

One Soft Failure posted from the former Primary:
Soft Failure 23 - Failure in OP circuit/field wiring detected by Analog Output/Digital
Output

A IOM Failover event
The following are likely if the fault was in the field:

Two Soft Failures posted by the new Primary:
Soft Failure 23 - Failure in OP circuit/field wiring detected by Analog
Output/Digital Output
Soft Failure 180 - Output Short Circuit Detected

The output unpowered
202 Series 8 I/O User's Guide
Honeywell
R500
April 2017