Programming instructions

32 bit counters

Presets

Presets are the number of times the rung driving the counter has to go

through a FALSE to TRUE state transition before turning on.

32 Bit counters have a range of –2,147,483,648 to 2,147,483,647.

Counter presets can be either a K constant, or a variable, such as a data

or file register. Having a D device as the preset allows an operator to

make changes to the counter preset from an HMI, or allows the preset to

be changed during operation of the logic.

The accumulated value of the 32 bit counter can exceed the preset value,

or go below 0. Once the counter coil has turned on, it will remain on until

reset, or the counter counts back down. Using the Decrement instruction

to reduce the count will not deactivate the counter coil.

Counting direction

32 bit counters can count up or down. Counting direction for counter

C### is based upon the status of relay M8###. If M8### is off, the

counter counts up. If M8### is on, the counter counts down.

i.e. For C201, direction is determined by M8201.

Reset

The accumulated value of a counter returns to 0 when the RST C#

instruction is activated.

32 bit counters addressed from C220 ~ C234 are latched counters and

retain their count even at power down. C200 ~ C219 will lose their counts

at power down unless they have been declared as battery-backed in PLC

Parameters

Limitations

Using the INCP instruction will make the counter count up and count pass

the preset. However, the counter coil will not be activated by reaching the

preset with the INCP instruction. The final count must come from a

FALSE to TRUE transition of the counter rung.

If a 32 bit counter has a negative preset, the logic works somewhat

differently than what may be expected. If the counter coil will activate only

when the preset is reached by counting UP to it from a SMALLER number

i.e. Counter C200 has a preset of –10. The as the counter counts down

from –9 to –10, the associated coil will not turn on. If the counter counts

down to –11 and then counts up to –10, then the coil will turn on.