7 Applied Instructions
7.14 Positioning Control
552
FXCPU Structured Programming Manual
(Basic & Applied Instruction)
Function and operation explanation
Cautions about writing during RUN
1) Avoid writing during RUN while DRVI or DDRVI is being executed (during pulse output).
(FX
3U, FX3UC, FX3G PLCs)
If, during pulse output, writing during RUN is attempted in circuit block including this instruction, it must be
noted that the pulse output slows down and stops.
2) While DRVI or DDRVI is being executed, the following writing during RUN is prohibited.
(FX
1S, FX1N, FX1NC PLCs.)
Program change of circuit block including this instruction.
Program change of circuit block immediately before or immediately after the circuit block including this
instruction.
Addition or deletion of circuit block immediately before or immediately after the circuit block including this
instruction.
Cautions
1) When handling 32-bit data in structured program, you cannot designate 16-bit device directly unlike the
simple project.
When handling 32-bit data, please use the label.
However, the 32-bit counter is a 32-bit long device, and 32-bit data can be specified directly.
When specifying the device, use the global label.
2) Instruction driving timing (FX
1S, FX1N, FX1NC PLCs)
This is an instruction allowed to program as many times as desired, but you are advised to design the
instruction driving timing according to the following cautions.
a) Do not drive simultaneously the positioning instruction using the same output relay (Y000 or Y001).
If driven simultaneously, it is handled as double coil, and normal function is disabled.
b) After turning OFF the direction input of the instruction, drive again after the following condition is
established.
Condition: Re-driving is allowed after one operation cycle or more from the OFF moment of "pulse
output mode monitor (Y000: [M8147], Y001: [M8148]" of the positioning instruction driven
previous time.
This is because one or more OFF operation is required for re-driving of the positioning instruction.
c) We recommend the step-ladder instruction (STL) as a method of programming correctly the
positioning instruction according to the cautions mentioned above.
DRVI
EN
s1
ENO
d1
d2s2
Number of output pulses (relative address)
Command
input
Output pulse frequency
Device for issuing pulse (Y)
Device of rotating direction signal
DDRVI
EN
s1
ENO
d1
d2s2
Command
input
Label 1
*1
Label 2
*2
Device for issuing pulse (Y)
Device of rotating direction signal
*1. Number of output pulses (relative address) is defined.
*2. Output frequency pulse is defined.
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