
B–61863E/15
2. SEQUENCE PROGRAMPMC SEQUENCE PROGRAM
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Input/output signals (assignment to the R, D, and E addresses) over a
network (such as the Ethernet, I/O Link–II, PROFIBUS, DEVICENET,
and FL–NET) are updated asynchronously with the execution of the PMC
sequence program. Therefore, when using the signals updated over a
network in the PMC sequence program, keep the following in mind.
(1)Notes on an input signal
When an input signal over a network is referenced at multiple points
in the PMC sequence program, there are not guarantees that the same
value can be referenced even in the same cycle in the sequence
program.
To guarantee that the same value can be referenced as an input signal
in the same cycle in the sequence program, save the status of the input
signal in the internal relay or the like.
(2)Notes on an output signal
An output signal over a network may be forwarded to a slave unit
during the operating cycle of the PMC sequence program. Be careful
when multiple signals are referenced on the slave unit side.
(3)Notes on multibyte data
The data concurrency (indicating that data is not broken) of multibyte
data input or output over a network is not guaranteed.
To ensure the data concurrency, the sequence processing performed
during data input and output must not cause data to be broken.
2.5.5
Notes on Input/Output
Signals Over a Network