Siemens SIMATIC ET 200AL, System Manual

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Applications of the F-I/O module
5.1 Digital input applications
Digital I/O module F-DI 4+F-DQ 2x24VDC/2A, 4xM12 (6ES7146-5FF00-0BA0)
Equipment Manual, V1.0, 05/2021, A5E51082342-AA
39
parameters and external component reaction times to achieve a total safety reaction time
goal.
In addition to the total delay from the safety demand input to the safe actuator response, you
must consider these additional time-related factors. Refer to "Maximum response time
(Page 83)" for exact information:
•
To be assured of a safety response, a safety demand signal from the input sensor lasts
long enough to be seen by the safety program. Your configured filter time, discrepancy
resolution time, and short-circuit test duration all contribute to determining the required
signal duration.
• The F-DI 4/F-DQ 2 Fail-Safe module digital outputs regularly test each P- and M-switch to
verify that each switch is still functional and under independent control. The OFF test
pulse duration can be as long as your configured "Maximum readback time". The ON test
pulse duration can be as long as your configured "Maximum readback time switch on
test". For a given output, the ON test pulse is only provided to one of the P- or M-switches
at a time, but in the presence of single fault this could apply energy to your load. Your
actuator should not respond to an OFF signal up to the "Maximum readback time"
duration, or to an ON signal up to the "Maximum readback time switch on test" duration.
• The F-DI 4/F-DQ 2 Fail-Safe module digital outputs expect to complete and confirm any
commanded transition from the ON to OFF output state. After your program changes the
process output value from "1" to "0", do not change the "0" back to a "1" until the output's
configured "Maximum readback time" has elapsed. The affected output passivates on
commanded "0" states that are too short to confirm.
WARNING
The safety performance of your installation depends on your design and continued
maintenance of each complete safety function.
The ET 200pro, ET 200SP and S7-1200/1500 Fail-Safe CPUs and F-DI 4/F-DQ 2 Fail-Safe
module provide components for logic processing with a certified level of safety integrity
when used in accordance with ratings, specifications, and instructions.
Failure to comply with these guidelines could cause damage or unpredictable operation
which could result in death or severe personal injury and/or property damage.
You must choose all components of your installation and complete your design and
maintenance according to accepted safety standards and practices to achieve your required
level of safety.
5.1 Digital input applications
You should consider the application modes presented here along with the features of the
F-DI 4/F-DQ 2 Fail-Safe module as described in the overview. Refer to "Fail-safe digital inputs
(Page 14)".