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Old November 14th, 2017, 11:21 AM   #1
illibilli
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one sensor two inputs

Just a quick newbie question.

Can I connect directly a digital sensor (reflective diffuse) to two independent PLCīs just by splitting up the cable, or is there a specific way to achive this. If it is possible on the other hand.

Thanks
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Old November 14th, 2017, 11:24 AM   #2
janner_10
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Yes, Just get the sensor to switch a relay and then use that to feed the 2 PLCs
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Old November 14th, 2017, 11:36 AM   #3
illibilli
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yup that will do the trick .

I feel kind of stupid now for not immediately figured that out.

Thanks Kind stranger.
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Old November 15th, 2017, 08:11 AM   #4
DwSoFt
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I'd the inputs are the same type you.could probably do it without the relay as well.
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Old November 15th, 2017, 05:58 PM   #5
ASF
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Quote:
Originally Posted by DwSoFt View Post
I'd the inputs are the same type you.could probably do it without the relay as well.
*Can* but probably *shouldn't*.

There was a thread about this exact topic a little while back - I'll see if I can find it - but the ultimate resolution was that yes, in very specific circumstances and if you take care of certain factors, you can make it work, but it's really not worth the potential headache when a $10 relay will do exactly what you want without any of the potential issues.
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Old November 19th, 2017, 10:35 PM   #6
Sergei Troizky
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If a relay has 5 million cycles mechanical life specification, and activates every second, it's theoretical life span is under 2 month of continuous operation.
Also, relay may be not fast enough device for short signals.
I would connect the 0V of both systems, and split the sensor signal to both PLCs, directly or via isolating diodes.
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