Siemens SIMATIC PCS 7 Operating Manual page 66

Configuring S7F/FH hardware
6.4 Setting system parameters for F-signal modules
Reintegration following a discrepancy error
You use this parameter to determine when a discrepancy error is considered lifted and,
therefore, when a reintegration of the affected input channels is possible. You can choose
between the following parameter options:
● "Test 0 signal necessary"
If you have configured "Test 0 signal necessary", a discrepancy error is only considered
lifted once a 0 signal is present at both input channels concerned.
If you employ non-equivalent sensors – i.e. "sensor evaluation" is configured to "1oo2
(2v2) non-equivalent evaluation" – then a 0 signal must be present at the lower value
channel of the pair.
● "Test 0 signal not necessary"
If you have configured "Test 0 signal not necessary", a discrepancy error is considered
lifted if no discrepancy is present any more at both input channels.
Time stamp
Changes to input signals are provided with a time stamp (date and time) during time
stamping and reported as a coming event.
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Compendium Part B - Process Safety (V8.2)
Operating Manual, 07/2016, A5E35031794-AB