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9.5.6 Interrogate PLC operands in the NC program (FN20: WAIT FOR)
1740
With FN20: WAIT FOR you can interrupt the NC program until the condition
programmed in the FN20 block is fulfilled. These conditions can be
comparisons of a PLC operand with a constant. Permitted PLC operands: M,
B, W, D, T, C, I, O and their symbolic operands
Operator
==
!= or <>
<
>
<=
>=
If you enter no condition, the interruption will continue until the operand = 0.
Examples:
FN20: WAIT FOR I10==1
Continue the NC program if PLC input I10 is set.
FN20: WAIT FOR I10
Continue the NC program if PLC input I10 equals zero.
FN20: WAIT FOR B3000>250
Continue the NC program, if the content of B3000 is greater than 250.
FN20: WAIT FOR is processed in look-ahead, i.e. if a synchronization with real
time is necessary, then FN20: WAIT FOR SYNC must be programmed in the
preceding NC block. Look-ahead is then stopped, and FN20: WAIT FOR is not
performed until this block is actually reached in the NC program.
Examples with symbolic operands:
FN 20: WAIT FOR TASTENCODE == 3 instead of
FN 20: WAIT FOR W274 == 3
Relational operands can also be symbolic. Example:
FN 20: WAIT FOR MARKER_A == MARKER_B
Function
Equal to
Not equal to
Less than
Greater than
Less than or equal to
Greater than or equal to
HEIDENHAIN Technical Manual iTNC 530 HSCI
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