Siemens SINAMICS S120 Function Manual page 235

Note
Discrepancy time
To avoid that fault messages are incorrectly triggered ("nuisance tripping"), at these inputs
the discrepancy time must always be set less than the shortest time between 2 switching
events (ON/OFF, OFF/ON) (see also the following diagram "Discrepancy time").
Further notes for setting the discrepancy time are contained in the "SINAMICS S120/S150
List Manual" for the following messages:
• F01611 (Basic Functions)
• C01770 (Extended/Advanced Functions)
T
S
T
D
T
R
Figure 5-5
● Second digital input with additional tap of the optocoupler cathode for connecting a
ground-switching output of a failsafe controller.
● The signal states of the two digital inputs of the F-DIs are frozen at logical 0 (safety
function selected) when different signal states are present within a failsafe F-DI until a
safe acknowledgment has been carried out by means of an F-DI via parameter p10006
(SI acknowledgment internal event input terminal).
● The monitoring time (p10002) for the discrepancy of the two digital inputs of an F-DI may
have to be increased so that switching operations do not trigger an undesired response,
thereby necessitating a safe acknowledgment. Therefore, the signal states at the two
associated digital inputs (F-DI) must have the same state within this monitoring time,
otherwise the following fault will be output F35151 "TM54F: Discrepancy error". This
requires safe acknowledgment.
Safety Integrated
Function Manual, 12/2018, 6SL3097-5AR00-0BP1
Switching interval
Discrepancy time
Response time
Discrepancy time
Control of the safety functions
5.4 Control via TM54F
233