Counter Counts Input Bit of Counter and Increment or Decrement by 1 When Input Bit of Counter Change. A counter use for counting of event, pulses and sequences. A Counter Input is always is Bit (ON or OFF), Pulses or Events. Increment counter which increment its preset value when input bit is change from true to false, decrement counter decrement preset value when input is change from true to false. In fuji PLC have two type of counter , Counter UP and Counter Down.

Fuji PLC Counter UP Instruction - CTU

Up counter (CTU) instruction is incremental counter, at every rising edge counter increments the current value by 1. if the current value reached to preset value than counter done bit is set to 1. When you add counter instruction in your rung so it required some basic parameter like counter number, counter preset value, counter input, reset of counter. Below shows the example of counter operation in fuji PLC.

• Counter Number : counter number represent the counter and hold the counter current value, range of counter number is C0 to C8191 for Local counter and for global counter range from C8192 to C16383. Counter number is also used as counter done bit.
• preset value: it is word type data range from 0 to 32767. You can also use constant value. Counter done bit is set when counter current reached to counter preset value.
• counter reset(CRST): counter reset instruction reset the above counter when input bit of reset counter is changed from 0 to 1.
• counter done bit: address of counter done bit is same as your counter number which you defined for counter instruction. This bit set to 1 when counter current value reached to counter preset value.

in above example of Fuji PLC Counter UP Instruction C0 is counter number, X1.0 is counter input bit, WM0 is word type Preset value of counter, X1.1 is a counter reset bit. For example if WM0 is equal to 10 so at every rising edge counter current bit increment by 1. When counter current value reached to counter preset value than counter done bit C0 is set to 1 and output Coil Y2.0 is set to 1. If the counter done bit is set to 1 and counter input bit is continue change from 0 to 1 so counter current value increment by 1 always. If Counter reset bit is changed from 0 to 1 than counter reset and counter current value is set to 0 and counter done bit is set 0(false) and

Fuji PLC Counter Down Instruction - CTD

Down counter (CTU) instruction is Decrement counter, at every rising edge of counter input, counter preset value decrement by 1. if the preset value reached to 0 than counter done bit is set to 1. basic parameter of Counter Down Instruction. Below shows the example of counter operation in fuji PLC.

• Counter Number : is same as counter up instruction.
• preset value: it is word type data range from 0 to 32767. you can also use constant value.
• counter reset(CRST): counter reset instruction reset the counter. if counter not reset and counter current value is 0 than counter input bit is change so counter current value continue to decrement to minus value.
• counter done bit: address of counter done bit is same as your counter number which you defined in your counter instruction. This bit set to 1 when counter current value reached to zero.

in above example of Fuji PLC Counter Down Instruction (CTD) C1 is counter number, X1.0 is counter input bit, WM4 is word type Preset value of counter, X1.2 is a counter reset bit. For example if WM0 is equal to 4 so at every rising edge counter current bit decrement by 1. When counter preset value reached to zero value than counter done bit C1 is set to 1 and output Coil Y2.1 is set to 1. If Counter reset bit is changed from 0 to 1 than counter reset and counter current value is set is equal to counter preset value and counter done bit is set 0(false).