■
Precautions for programming
● If a hold type memory area is specified for the elapsed value area, the elapsed value acts in
accordance with the content being held.
● Be aware that the default value when starting operation is not automatically preset to the
elapsed value area. When performing preset, switch reset input from ON to OFF.
● When using an UDC instruction with an AND stack (ANS) instruction or pop stack (POPS)
instruction, be sure to write the code correctly.
■
Cautions on detecting the count input
● The UDC instruction detects rising from OFF to ON of the count input and increments or
decrements the set value.
● Counting is only performed at the rise, so even if the count input remains on, no further
counting will occur.
● The set value will not be incremented or decremented for the first scan if the count input is
already ON when the operation mode is switched to RUN or the power is turned on in the
RUN mode.
Count input
Instruction
operation
RUN
(Power on)
Counted
Not counted
● Be careful when using this instruction with an instruction that changes the order of instruction
execution such as MC - MCE or JP - LBL (1 to 6, shown below), because the operation of
the instruction may change depending on the timing of the instruction execution and count
input.
1) MC - MCE instructions
2) JP - LBL instructions
3) LOOP - LBL instructions
4) CNDE instruction
5) Step ladder instructions
6) Subroutine instructions
3.22 UDC (Up/Down Counter)
3-68 WUME-FP7CPUPGR-12
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