I/O - ABB FSO-21 User Manual

If an FSO I/O or a safety fieldbus failure occurs, the FSO module activates the SSE
function (or the STO function, if an STO request is connected to the I/O). In other
internal failure situations, the FSO module activates the STO function. Depending on
parameter settings, the SSE function can be similar to the STO function (when
configured as "Immediate STO", for more information see section
page 284).
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I/O

The FSO module supports input and output redundancy.
The FSO module provides an option for applying diagnostic pulsing for its inputs and
outputs. When applied, the pulsing enables the FSO diagnostics to detect cable
failures as follows:
• Inputs: Open-circuiting and short-circuiting failures are detected with diagnostic
pulsing. The failures that short-circuit the sensor are detected upon input
activation when redundant connection is used.
1
1
1
Note: If only one of the redundant inputs is activated upon a safety function
request, the FSO module activates the safety function but it cannot be
acknowledged before the failure has been repaired. To acknowledge the safety
function, you must set both input channels down and up at the same time or,
switch the power off and on.
• Outputs: If diagnostic pulsing is used, failures that short-circuit the signal to the
voltage supply or the ground potential are detected. Failures that open-circuit the
actuator are not detected.
TP2
Diagnostic pulse 2
Diagnostic pulse 1
TP1
2
DI1 Digital input 1
DI2 Digital input 2
Safety information and considerations 31
1. Failure is detected
2. Failure is detected upon
input activation when
redundancy is used
Configuring SSE on