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Process interfacing via an automation system (PLC, PC)
9.4 Control with FB 79
It then queries the program now selected on the optical reader and outputs it at the
"CODE_OUT" parameter.
If the program now selected matches the program specified at the "PARAM1" parameter, the
"ACTIVE" parameter has the value "FALSE" and the "DONE" parameter the value "TRUE". If
the program now selected does not match the program specified at the "PARAM1"
parameter, the "ACTIVE" parameter has the value "FALSE" and the "ERROR" parameter the
value "TRUE". The "ERRCODE" parameter contains an appropriate error message. The
system also checks whether program saving is being blocked by a "Service" or "User1" user
logged on in the WBM who has taken over control of the optical reader, and whether the
program was saved successfully.
If an error is detected, the "ACTIVE" parameter has the value "FALSE" and the "ERROR"
parameter has the value "TRUE". The "ERRCODE" parameter contains an appropriate error
message.
If you attempt to cancel a current save program job, the "ERRCODE" parameter will change
to "DW#16#00000002"; however, processing for the job will be completed.
Sequence when outputting the currently selected program ("COMMAND" = W#16#0003)
When the job is triggered, the parameters "DONE" and "ERROR" have the value "FALSE".
The "ACTIVE" parameter has the value "TRUE".
The block then queries the program now selected on the optical reader and outputs this
program at the "CODE_OUT" parameter.
If no error occurs in the transfer of the program number, the "ACTIVE" parameter will have
the value "FALSE" and the "DONE" parameter the value "TRUE".
Sequence when outputting the operating state of the optical reader ("COMMAND = W#16#0004")
Based on the status byte of the optical reader, the block recognizes the current state and
outputs this in the "STATE" parameter. Note the following points:
● If the "IN_OP" bit is not set, status 3 ("ERROR") is output.
● If the "IN_OP" bit is set but not the "RDY" bit, status 2 ("STOP") is output.
● If the "IN_OP" bit and the "RDY" bit are set, status 1 ("RUN") is output.
The "DONE" parameter then has the value "TRUE" and "ACTIVE" the value "FALSE".
Note
No edge change detected
Because the job completes in one CPU cycle, no edge change can be detected at the
"ACTIVE" parameter. If the "DONE" parameter already has the value "TRUE" from a
previous job, it is also not possible to detect an edge change.
148
Operating Instructions, 05/2019, C79000-G8976-C494-02
SIMATIC MV500
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