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PLC User's Manual - Positioning Control Edition
Built-in Positioning Functions
10 Variable Speed Operation (Variable Speed Pulse Output)-PLSV Instruction
10.4 Important Points
B - 140
10.4 Important Points
→ For important programming points, refer to Section 4.7.
• During pulse output operation, if the output pulse frequency is changed to "K0", the PLC will reduce
the speed and then stop the pulse outputting operation if the acceleration/deceleration function is ON.
However, if the acceleration/deceleration function is not activated, the PLC will immediately stop the pulse
outputting operation.
Before outputting pulses again, check that the "pulse output monitor" (BUSY/READY) flag is off, and then
wait until 1 or more cycles of operation have been completed. After that, set (change) the output pulse
frequency to a value other than "K0".
• During pulse outputting operation, do not change the sign attached to the output pulse frequency
value .
If it is necessary to change the sign, stop the servo motor first by setting the output pulse frequency value
to "K0", and wait for the motor to stop completely after decelerating to stop. And then, change the
sign attached to the output pulse frequency value .
If the sign attached to the output pulse frequency value is changed during pulse outputting
operation, the operation may be changed as follows, and the machine, therefore, may be damaged:
1) The pulse outputting operation may be stopped.
2) "Pulse output monitor" (BUSY/READY) flag may be turned off.
(The pulse outputting operation may be stopped, but the motor may not be stopped immediately.)
3) Operation may be performed in the specified direction at the frequency specified by the output
pulse frequency value .
• If the instruction activation contact is turned off during pulse outputting operation while the acceleration/
deceleration function is ON, the speed will decelerate and the operation will stop.
If the instruction activation contact is turned off during pulse outputting operation while the acceleration/
deceleration function is OFF, the operation will stop immediately. In both cases, the "Instraction execution
complete" flag (M8029) will not turn on.
• If a limit flag (forward / reverse rotation) in the operation direction is turned on, the operation will stop
immediately. In this case, the "Instruction execution abnormal end" flag (M8329) will turn on when
execution of the instruction is complete.
→ For details on the "Instruction execution abnormal end" flag, refer to Subsection 4.7.4.
• If the "pulse output monitor" (BUSY/READY) flag is on, a positioning instruction (including PLSR and
PLSY) that uses the same output cannot be executed.
If the "pulse output monitor" (BUSY/READY) flag is still on after the instruction activation contact is turned
off, do not execute a positioning instruction (including PLSR and PLSY instructions) that uses the same
output number.
• After executing the instruction, the rotation direction signal output will turn off.
1. Important items for FX3UC PLCs below Ver.2.20
• Acceleration/deceleration will not be performed when starting or stopping the operation. For this reason, if
it is necessary to use the cushion start function or the cushion stop function, increase/decrease the output
pulse frequency value using the FNC67 (RAMP) instruction, etc.
2. Important items for FX3U/FX3UC PLCs Ver.2.20 or later and FX3G
PLCs
• If acceleration/deceleration is enabled, the variable speed pulse output (PLSV) instructions for all of the
pulse output destination devices will use acceleration/deceleration. This means that acceleration/
deceleration cannot be specified separately for each pulse output destination device.
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