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20 Applied Instructions (Positioning Control)
20.8 DRVA / Drive to Absolute
538
FXCPU Structured Programming Manual
[Basic & Applied Instruction]
Cautions about writing during RUN
Avoid writing during RUN after either of the following operations in a circuit block including the pulse output
instruction or positioning instruction.
• Changing a program for a circuit block including a corresponding instruction.
• Changing a program for a circuit block just before or after a circuit block including a corresponding
instruction.
• Deleting or adding a circuit block just before or after a circuit block including a corresponding instruction.
This caution about the above operations is applicable to the following PLCs and instructions.
FX
1S, FX1N and FX1NC PLCs : PLSY, DPLSY, PWM, PLSR, DPLSR, ZRN, DZRN, PLSV,
DPLSV, DRVI, DDRVI, DRVA and DDRVA
FX
2N and FX2NC PLCs : PLSY, DPLSY, PWM, PLSR and DPLSR
FX
3S, FX3G, FX3GC, FX3U and FX3UC PLCs: DSZR, DVIT
*1
, DDVIT
*1
, DTBL
*2
, ZRN, DZRN, PLSV, DPLSV,
DRVI, DDRVI, DRVA and DDRVA
Note that the pulse output will decelerate and stop when writing during RUN is executed in the FX
3S, FX3G,
FX
3GC, FX3U or FX3UC PLC.
*1. Not available for the FX
3S, FX3G or FX3GC PLC.
*2. Not available for the FX
3S PLC.
Cautions
1) Instruction driving timing (FX1S, 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.
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) Some restrictions to applicable devices.
S1: <FX
3S, FX3G, FX3GC, FX3U, FX3UC PLCs>
Please specify Y000, Y001, Y002
*1
of transistor output of basic unit, or Y000, Y001, Y002
*3
, Y003
*3
of high speed output special adapter
*2
.
*1. The pulse output destination Y002 is not available in FX
3S, FX3G (14-point and 24-point type)
and FX
3GC PLCs.
*2. High speed output special adapter can be connected only in FX3U PLC.
*3. When using Y002, Y003 in high speed output special adapter, a second high speed output
special adapter is needed.
Points
• When using FX3U PLC of relay output type or triac output type, high speed output special
adapter is needed.
• The output of high speed output special adapter is a differential line driver.
<FX
1S, FX1N, FX1NC PLCs>
Specify Y000 or Y001.
As the output of the PLC, please use the transistor output.