Help needed - to find time between 2 input signals

Preeya · Jan 7, 2004

Hi everyone, I have an input that changes state frequently (in milliseconds). I need to find the time interval between 2 signals of this input. (ref diagram)

I tried to set a timer and reset it with the same input but it didn't seem to work. I am using a siemens S7 200 PLC.

Please help me! Thanks

ArikBY · Jan 7, 2004

Try this, it made by Omron but the general idea is a same.

ArikBY · Jan 7, 2004

If it not work you might need to do it by interrupt.
You need to see how it done by Siemense.

Preeya · Jan 7, 2004

Thanks for the logic Arik. Let me try that and see. But as I mentioned this input changes in millisecs so hopefully this logic works.

Siemens S7 200 has Input rising edge interrupt. But how do I use that? Also as this input changes frequently wouldn't the interrupt keep executing?

tesalmin · Jan 7, 2004

Try this.

I couldn't test it because I haven't simulator for S7-200 or any S7-200 PLC:s.

There are some 1ms resolution timers in S7-200 according to Microwin help: (TONR--> T0,T64 - TON,TOF-->T32,T96)

ArikBY · Jan 7, 2004

You can put the value in shift register and get line og data

Preeya · Jan 7, 2004

This logic seems to work.. I just tested on the S7 200. Thanks TS!

Thanks for your help too Arik.

Manuel Raposo · Jan 7, 2004

Hi,

If you try it with a Mitsubishi FX2N, you can use the first inputs with interrupts amd measure time input is ON, time OFF or period.

Can be measured with a resolution of 0.1ms.

Help needed - to find time between 2 input signals

Preeya

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ArikBY

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ArikBY

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Preeya

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tesalmin

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ArikBY

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Preeya

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Manuel Raposo

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