Timer Processing And Accuracy - Mitsubishi Electric MELSEC-A Series User Manual

4.A2CCPU
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4.1.4 Timer processing and accuracy
The A2C uses up-timing timers which increase present value as measuring
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time increases. Three kinds of timers are provided; 100 msec timer, 10 msec
timer and 100 msec retentive timer.
• 100 msec timers ... setting range:
0.1 to 3276.7 sec in 100 msec increments
• 10 msec timers ... setting range:
0.01 to 327.67 sec in 10 msec increments
• 100 msec retentive timers ... setting range:
0.1 to 3276.7 sec in 100 msec increments
Processing when the coil is turned off differs from the processing of 100
msec timers.
The following paragraphs explain timer processing.
(1) Timer present value and contact status update
With continuity in front of a timer coil, the timer present value and
contact status are updated after the execution of the END (of FEND)
instruction and the timer contacts close after the timer has timed out.
(a) 100 msec and 10 msec timers
When the continuity is removed from in front of the timer coil, the
present value is reset to 0 and the timer contacts open.
(b) 100 msec retentive timer
When the continuity is removed from in front of the timer coil, the
present value update is stopped but the present value is retained.
(2) RST T[ ) instruction executed
When the timer is reset by the RST T[ ) instruction, the present value is •
reset to 0 and the timer contacts open. The retentive timers retain their
present value and contact status, and are reset using the RST T[ )
instruction.
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