Siemens SIMATIC ET 200AL, System Manual

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Programming
4.3 Time-based IO
High-precision input/output with Time-based IO
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Function Manual, 11/2019, A5E33454822-AC
You start an output job with a positive edge at the REQ parameter. You can only start a new
job when there is no error pending and no job is active. When the output job is started, the
digital output is switched at the times defined with TimeStampRE and TimeStampFE.
● If the digital output is already set at time TimeStampRE, the output job is not transferred
to the module for the positive edge.
● If the digital output is not set at time TimeStampFE, the output job is not transferred to the
module for the negative edge.
This means the digital output is not switched in both cases.
The job is done when the last application cycle is executed before the second output time is
reached (DONE). Status and Error are constantly being updated during the job runtime. You
can cancel an active output job by changing TimeStampRE or TimeStampFE to an invalid
time stamp, e.g. LT#5μs.
The figure below shows an example for the reaction of the bits DONE and BUSY at the start
of an output job under the following conditions:
● Out_Mode = 2 (both edges are output)
● The two time stamps are not changed between the start of the job and the output.
T
APP
Application cycle
R1, R2 Specified times of a positive DQ edge
F1, F2
Specified times of a falling DQ edge