Time For Short-Circuit Test - Siemens Simatic S7-1500 Manual

Parameters/address space
4.2 Explanation of parameters
The short-circuit detection switches off the internal sensor supply briefly. The length of the
deactivation period is equivalent to the configured "Time for sensor test".
If a short-circuit is detected, the F-module triggers a diagnostic interrupt and the input is
passivated.
The following short-circuits are detected:
● Short-circuit of input to L+
● Short-circuit of the input of another channel when it has a 1 signal
● Short-circuit between the input and sensor supply of another channel
● Short-circuit between the sensor supply and the sensor supply of another channel
If the short-circuit test is disabled, you must make your wiring short-circuit and cross-circuit
proof or select a connection type (discrepancy, non-equivalent) which also detect the cross-
circuits using discrepancy.
Note
During the execution time of the short-circuit test (Time for short-circuit test + Startup time of
sensors after short-circuit test), the last valid value of the input before the start of the short-
circuit test is passed to the F-CPU. The activation of the short-circuit test thus affects the
response time of the respective channel or channel pair.
4.2.2.3

Time for short-circuit test

Function
When the short-circuit test is enabled, the corresponding internal sensor supply is switched
off for the configured time. If the module does not detect a "0" signal at the input within the
configured time, a diagnostics alarm is generated.
Note the following during parameter assignment:
● If the channel is passivated, this may be due to excessively high capacitance between
sensor supply and input. This consists of the capacitance per unit length of the cable and
the capacitance of the employed sensor. If the connected capacitance is not discharged
within the configured time, you need to adjust the "Time for short-circuit test" parameter.
Note
During the execution time of the short-circuit test (Time for short-circuit test + Startup time
of sensors after short-circuit test), the last valid value of the input before the start of the
short-circuit test is passed to the F-CPU. The activation of the short-circuit test thus
affects the response time of the respective channel or channel pair.
● The "Time for short-circuit test" has to be 0.5 ms greater than the set input delay.
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Digital input module F-DI 16x24VDC (6ES7526-1BH00-0AB0)
Manual, 01/2016, A5E03858068-AA