Max. Readback Time Switch-On Test - Siemens SIMATIC S7-1500 Manual

Parameters/address space
4.2 Explanation of parameters
4.2.3.6

Max. readback time switch-on test

Function
The switch on test is part of the bit pattern test.
PM operation
During the switch-on test in PM operation, the P-switch and M-switch of the output channel
are alternately closed and read back when the output channel is inactive (output signal "0").
Contrary to the light test, no power flows through the connected load during the switch on
test.
①
Image 4-4
In case of an error, the bit pattern test can apply voltage to the load up to a duration that
was configured with the "Maximum readback time switch on test" parameter.
For capacitive loads, it can happen that these are not actively discharged in the event of an
error.
Therefore, always configure a maximum readback time that cannot activate the load under
any circumstances.
26
Readback
Functional principle of the switch on test (PM switching)
WARNING
Digital output module F-DQ 8x24VDC/2A PPM (6ES7526-2BF00-0AB0)
Manual, 01/2016, A5E03858037-AA