Handling Of Input Signals Designated For High-Speed Input - Mitsubishi Electric MELDAS C6 Programming Manual

Table 3.1-1 lists whether or not high-speed input/output, interrupt input and initial processing can be
performed.
Table 3.1-1 Whether or not high-speed input/output, interrupt input and initial
can be performed
Input signal from control unit
Output signal to control unit
Input signal from machine
Output signal to machine
Input signal from operation
board
Output signal to operation board
: Possible x : Not possible
(Note 1) The operation board here refers to when the remote I/O is installed on the communication
terminal.

3.2 Handling of Input Signals Designated for High-Speed Input

The input/output signals used in user PLC are input/output for each program level as shown in
Fig. 3.1-2.
In high-speed processing, input/output signal for which high-speed input or output designation
(parameter) is made is input or output each time the high-speed processing program runs. In main
processing, signals other than the high-speed input/output designation are input/output.
When high-speed input designation signal is used in main processing, the input signal may change
within one scan because high-speed processing whose level is higher than main processing
interrupts. Input signal which must not change within one scan should be saved in temporary memory
(M), etc., at the head of main processing and the temporary memory should be used in the main
program, for example.
Input image memory
The hatched area is high-speed input designation part. Whenever the high-speed processing
program runs, data is reset in the hatched area. Thus, the signal in the hatched area may change in
main processing (A) and (B) because the high-speed process interrupts between (A) and (B) and
re-reads the input signal in the hatched area.
3. Input/Output Signals
3.1 Input/Output Signal Types and Processing
High-speed input
specification
(2-byte units)
Main
processing
(1)
High-speed
processing
(2)
(1) Set at the head of main processing.
(2) Set at the head of high-speed processing.
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High-speed output
x
x
x
x
x
PLC on e scan
A B
specification
x
x
x
(2-byte units)
x
x