Siemens PLC's counting instructions - Solutions - Huaqiang Electronic Network

Brand AVX TPSE226M035R0125 Low impedance tantalum capacitor, AVX 22

Electronic scale crystal oscillator, 3.2x2.5mm, 3225, 16MHz (16.000MHz), 12PF, 10PPM, 20PPM, 30PPM

SMD aluminum electrolytic capacitor

Photocoupler

When the up-count input of a Siemens PLC transitions from off to on, the Up Counter (CTU) increments its current value. The counter resets when the reset input is activated or when a reset command is executed. Once the maximum value of 32,767 is reached, the counter stops incrementing and remains at that value. The Up/Down Counter (CTUD) functions by counting up when the up-count input transitions from off to on, and counting down when the down-count input transitions from off to on. If the counter reaches 32,767 and another up transition occurs, it will roll over to -32,768. Conversely, if it reaches -32,768 and a down transition occurs, it will roll back to 32,767. This allows for bidirectional counting in applications requiring both increase and decrease functionality. Each counter has a current value that stores the present count. Additionally, there is a preset value (PV) that determines the target value. The C bit is activated whenever the counter instruction is executed and the current value matches the preset value. Otherwise, the C bit remains inactive. The Down Counter (CTD) decreases its current value each time the down-count input transitions from off to on. When the load input is turned on, the counter resets its current value to zero and loads the preset value into the counter. Once the count reaches zero, the counter stops and the C bit turns on. When using the Siemens PLC reset command, the counter bit is cleared, and the current value is set to zero. This ensures the counter starts fresh for the next operation. The counter value can be used to monitor the current state of the counter and the status of the C bit. Note: Since all counters share the same current value register, it is important not to assign the same counter number to more than one counter. This applies to the Up Counter (CTU), Up/Down Counter (CTUD), and Down Counter (CTD). Using duplicate numbers may lead to unexpected behavior or errors in your program.