Siemens SIMATIC S7-1500 Manual page 24

Parameters/address space
4.2 Explanation of parameters
Setting readback time dark test with unknown actuator capacity
If the capacity of the actuator is not known, it may be necessary for you to determine the
value for the readback time dark test by trial and error. This may also be necessary due to
the part variances in the actuator or external influences.
Proceed as follows:
● Set the readback time dark test so that the output channel can be read back correctly but
your actuator does not respond yet.
● For verification use the process value "1" with a minimum duration that corresponds to
the "maximum test time" parameter.
● If the output channel is passivated sporadically, set a higher value for the maximum
readback time dark test.
● If the output channel is passivated, the readback time dark test is too small for a
connected capacitive load. The discharge cannot take place during the configured
readback time dark test. Increase the readback time dark test.
If you have set the readback time dark test to the maximum value of 400 ms and there is still
a passivation of the output channel, there is either an external fault or the connected
capacity is outside the permitted range.
To increase availability, we recommend that you maintain an interval to the determined limit
for the times.
Test pulses of the dark test
*
Image 4-3
The interval between two test pulses is 500 ms.
24
Output of test pulses only during test cycle.
Test pulses of the dark test
Digital output module F-DQ 8x24VDC/2A PPM (6ES7526-2BF00-0AB0)
Manual, 01/2016, A5E03858037-AA