Yaskawa MP940-MW+ - Manual (Page 14)

TECHNICAL NOTE
MOTION PRODUCT AND ENGINEERING GROUP
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5/22/2003 14 of 34 eng/PubNumber/MCD
timed out, the subroutine ends and execution is returned to the main calling program. If the input
(input 5) that calls the subroutine is left on the subroutine will be executed again (and again).
The set variable block (3) activates output 5; corresponding block (7) deactivates the
output. Making the output correspond to an “in motion” indicator. The next block, Timer (8)
delays by a user variable [MoveDelay]. Set variable block (9) deactivates any outputs that may
be left on from the PLS. Execution continues to another timer block, with the same user variable
as the earlier timer block.
Programmable Limit Switch (PLS)
As the controlled axis is configured in linear mode, the system variable mPosition_Actual
counts up forever (actually until the 32-bit register rolls over, then it counts up again). Therefore,
the current position prior to the move is captured in block 3 in the user variable PositonCapture.
Then mPosition_Actual-PositionCapture is be used as the “Encoder Variable” in the PLS block
(5). With this method the PLS block is modularized automatically per move.
The PLS block implemented in this project is executed in this subroutine and therefore
relies on the Move Block (4) Wait for completion box to be un-checked. It is used in conjunction
with the If Event Block (6) that checks for the move to be complete (system variable
mPosition_Complete), the PLS is updated while in motion.
Entries for (Value >) and (< Value) can be implemented as fixed numbers, user variables,
system variables, and any combination thereof. In addition, the entries can be calculations,
especially useful for applications where PLS outputs also depend on speed of machine. Be
careful with calculation syntax, as ‘C’ syntax is followed. Lastly, when implementing values that
go through (past) zero, it is best to split them up in to two segments [(Value>) to 0] and [0 to
(OR
ed together to set the correct output.
Timer
The last few blocks (7-10) are
comprised of set variable and timer
blocks. Some special attention should be
brought up regarding the Timer block.