How It Works - Siemens SIMATIC MV540 H Operating Instructions Manual

When a new job is started, the output parameters are reset.
Note
Multiple calls of FB 79 with the same instance is not permitted
Note that making multiple calls of FB 79 with the same instance is not permitted
Note that you can use the parameters in the "Settings > Communication > Use" menu of the
WBM to influence the sequence of command execution of the function block:
● If you want to read out a result string using the function block, the output of the result
string must be set to PROFINET IO. With the jobs "Select program" (COMMAND
=W#16#0001), "Save a program" (COMMAND =W#16#0002) and "Output currently
selected program" (COMMAND =W#16#0003), the number of the selected program is
queried by the optical reader. For this reason, output of the result string must also be set
to PROFINET IO in these cases.
● The interface for the "DISA", "SEL0" to "SEL3", "TRN", "RES", "IN_OP", "TRD", "RDY"
signals must always be set to PROFINET IO.
● The setting of the interface for the result bits "READ", "MATCH", "N_OK" is irrelevant for
the function block.
9.4.5.1

How it works

FB 79 "VS130-2_CONTROL" is an asynchronous block. This means the processing can
extend over several block calls. You start job execution by calling the FB with a job number >
"0".
Job execution is completed when the "ACTIVE" parameter changes to the value "FALSE"
and either "DONE" or "ERROR" has the value "TRUE" (positive edge). Note that various jobs
can be handled in one CPU cycle and the "ACTIVE" parameter does not therefore change to
the value "TRUE". This involves the "Read out status" and "Reset DISA bit" jobs. In this
case, it may also not be possible to detect an edge change at "DONE" or "ERROR".
You should therefore process the "DONE" and "ERROR" parameters at each block call. If
the job was completed without error, "DONE = TRUE" is set. Always process the
"ERRCODE" parameter to get warnings from the FB.
As long as the "ACTIVE" parameter has the value "TRUE", you must call the FB with
identical assignment of the "COMMAND" input parameter. It is also not possible to start a
new job during this time.
Read jobs are cyclic jobs. This means that after starting a job with "COMMAND =
W#16#0081 ... 008F", the "ACTIVE" parameter assumes the value "TRUE". "ACTIVE"
retains this value until the job is canceled or stopped.
The read cycle (in other words, the transfer of a complete result string) is completed when
the "ACTIVE" parameter has assumed the value "TRUE" and either "DONE" or "ERROR"
has assumed the value "TRUE" (positive edge). If you want to start a different job while a
read job is running, you will need to cancel the read job first. This is done by calling the FB
with "COMMAND = W#16#0000". In this case, the "ACTIVE" parameter assumes the value
"FALSE". Depending on whether a result string is currently being transferred, either "DONE"
SIMATIC MV500
Operating Instructions, 06/2018, C79000-G8976-C494-01
Process interfacing via an automation system (PLC, PC)
9.4 Control with FB 79
141