
B-63983EN/02 1.OVERVIEW OF PMC
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Input signal processing
(1) Input memory of the CNC
Signals input from the CNC to PMC are set in the memory of the
CNC and are normally transferred to the PMC at intervals of 4 or
8 msec. Since the 1st and 3rd level sequence parts directly
reference and process these signals, these signals are not
synchronized with input signals from the CNC. See the
description of following “Notes on programming asynchronous
I/O signals”.
(2) Input signals from the machine (DI/DO card)
Signals input from the machine are transferred to the input signal
memory via the input circuit (DI/DO card). The 1st and 3rd level
sequence parts read the input signals from the input signal
memory and process them.
(3) Input signal memory
The input signal memory stores signals transferred from the
machine at intervals of 2 msec.
The 1st and 3rd level sequence parts of the PMC read and process
signals stored in this memory. In this case, the signal set in the
input signal memory is not synchronized with the 1st and 3rd level
sequence parts. For notes on asynchronous processing, see the
description of following “Notes on programming asynchronous
I/O signals”.
(4) 2nd level synchronous input signal memory
The 2nd level synchronous input signal memory stores signals
processed by the 2nd level sequence part of the PMC. Signals
synchronized with the 2nd level sequence part are set in this
memory.
Input signals in the input signal memory and input signals from
the CNC are automatically transferred to the 2nd level
synchronous input signal memory at the beginning of the 2nd
level sequence part. Therefore, the status of the 2nd level
synchronous input signal memory is kept unchanged during the
time from the beginning of the 2nd level sequence part until the
end of the sequence part.
The programmer function automatically performs processing so
that the 1st and 3rd level sequence parts use input signals in the
input signal memory and input signals from the CNC while the
2nd level sequence part uses the 2nd level synchronous input
signal memory. (This need not be considered during
programming.)