Safety Manager Safety Manual - Tuv-fs.com

SM IO faults
Table 13 on page 31 shows the relation between Input and output compare faults,
alarm markers and Controller response.
Table 13 Controller response to IO compare faults
IO compare error
Related to redun
dancy
Occurs when detecting
digital inputs N.A. a persisting difference for more than 2
application cycles
analog inputs N.A. a deviation of >2% for more than 2
application cycles.
digital N.A. a difference between outputs
outputs
analog N.A.
outputs
Controller
response
apply FR
state
Compare error detection and synchronization
Input compare errors
Input compare error detection applies to all hardware inputs.
Differences in the input status read should be momentary. Persisting differences
could be the result of detected hardware faults. In that case, the faulty input
channel is reported in the diagnostics, and both Control Processors use the
process value read from the healthy input channel.
A persisting difference in status of an input while no faults are detected at the
accessory hardware channels leads to an input compare error.
Output compare errors
An output compare error applies to all hardware outputs.
In configurations with a redundant Controller, both Control Processors will
continuously have an identical application status, resulting in identical process
outputs.
An output compare error is detected if there is a difference between the Control
Processors with respect to:
• the calculated application output values for hardware outputs (AO/DO) or
communication outputs (DO, BO) to another Safety Manager.
• the actual application values sent to hardware outputs (AO/DO) or
communication outputs (DO, BO) to another Safety Manager.
Safety Manager Safety Manual 31