Siemens SIMATIC Operating Instructions Manual page 95

Reintegration After Discrepancy Error Parameter
This parameter is used to specify when a discrepancy error is regarded as eliminated and,
thus, when the relevant input channels can be reintegrated. The following can be assigned:
● "Test of 0-signal required" or
● "Test of 0-signal not required"
Requirements
You have assigned the following:
● Evaluation of the sensors: "1oo2 evaluation"
"Test of 0-signal required"
If you assigned "Test of 0-signal required", a discrepancy error is regarded as eliminated
once a 0-signal is present again at both of the relevant input channels.
If you are using nonequivalent sensors, i.e., the "Type of sensor interconnection" is set to "2-
channel nonequivalent", a 0-signal must be present again at the channel supplying the
wanted signal.
For information about which F-module channels supply the wanted signals, refer to the
manual for the F-module you are using.
"Test of 0-signal not required"
If you assigned "Test of 0-signal not required", a discrepancy error is regarded as eliminated
once the discrepancy at the two relevant input channels disappears.
F-modules in SIMATIC S7 for which the "Reintegration after discrepancy error" parameter is
not available also exhibit this behavior.
Readback Time Parameter
Each output channel has its own assignable readback time. This time specifies the maximum
duration of the switch-off test for the corresponding channel and, thus, also the readback
time for the switch-off operation of the channel.
The following readback times can be assigned: 1 ms, 5 ms, 10 ms, 50 ms, 100 ms, 200 ms,
and 400 ms.
You should set a sufficiently long readback time if the relevant channel switches high-
capacitive loads. If the readback time for a controlled capacitive load is set too low, the
output channel is passivated because the discharge of the capacitance does not take place
within the switch-off test.
In the event of false readback signals, an amount of time equivalent to the readback time is
permitted to elapse before the "short circuit" fault causes the output channel to become
passivated.
ET 200pro Distributed I/O System - Fail-Safe Modules
Operating Instructions, 05/2007, A5E00394073-02
8.2 4 /8 F-DI/4 F-DO DC24V/2A PROFIsafe Digital Electronic Module
Fail-Safe Electronic Modules
95