Ladder program checks pulses in a time window

[Sergio Bertana]

The request of a Customer is to verify if within a time window activated by a strobe input two digital signals both have two variations and to signal the Ok or error condition at the end of the time window.

I prefer to write programs in ST language but since the customer asks me if it is possible to have a program in Ladder diagram, I made the program PulseCheck of which I attach download. We follow the flow from the program printing.

• Rung 1: On the activation front of the input Strobe the control timing timer and signal are activated CStrobe.
• Rung 2: On the activation front of the input Strobe all variables are initialized.
• Rung 3: On the activation front of the input ASignal the relative counter is increased.
• Rung 4: On the activation front of the input BSignal the relative counter is increased.
• Rung 5: On the front of the deactivation of the signal CStrobe (End of control time window) occurs if both counters have assumed value 2. If the condition is verified, the Ok.
• Rung 6: On the front of the deactivation of the signal CStrobe if not the condition of Ok the condition is set Error.

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