Mitsubishi MELSEC-Q QD77MS, User Manual

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Chapter 9 Major Positioning Control
POINT
• When the movement amount is converted to the actual number of command
pulses, a fraction appears after the decimal point, according to the movement
amount per pulse. This fraction is normally retained in the QD77MS and reflected
at the next positioning.
For the fixed-feed control, since the movement distance is maintained constant
(= the command number of pulses is maintained constant), the control is carried
out after the fraction pulse is cleared to zero at start.
[Accumulation/cutoff for fractional pulses]
When movement amount per pulse is 1.0 [
μ
m] and movement for 2.5 [
μ
m] is
executed two times.
→
Conversion to command pulses: 2.5 [
μ
m] ÷ 1.0 = 2.5 [PLS]
2PLS
2PLS 2PLS
3PLS(=2.5+0.5)
Movement
amount
0.5 PLS hold by the QD77MS is
carried to next positioning.
INC Linear 1
Fixed-feed 1
0.5 PLS hold by the QD77MS is
cleared to 0 at start and not
carried to next positioning.
2.5 m 2.5 m