PaulKim1003

SInk plc input module

11 posts in this topic

Hi,

i am trying to wire a sensor to plc input card.

I have sink input modules, if i want to wire a sensor, does the sensor has to be sinking module too?

any help will be appreciated.

Thanks

 

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Thanks for the reply.

Does that mean i can not use NPN sensor if i have a sinking PLC input moduel??

 

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17 minutes ago, PaulKim1003 said:

Thanks for the reply.

Does that mean i can not use NPN sensor if i have a sinking PLC input moduel??

 

I don't know. I have only seen NPN sensors a few times in my experience, and every time I replaced them with PNP sensors to make them easier to use. (In my case the sensors were inexpensive to replace)

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You can use the NPN output of a sensor but if the sensor doesn't have a built-in pull-up resistor, you'll have to add one externally. Can you tell us what sensor and input module you're using?

 

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"sinking plc input card" and "NPN sensor"? what are the actual products you plan on using?

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Sensor with NPN (Sinking) output should be used with PLC Sourcing Input.

Sensor with PNP (Sourcing) output should be used with PLC Sinking Input.

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4 minutes ago, Wasan said:

Sensor with NPN (Sinking) output should be used with PLC Sourcing Input.

Sensor with PNP (Sourcing) output should be used with PLC Sinking Input.

theoretically yes... if both products are made by companies using same terminology

but "sinking/sourcing" is not used consistently and if i recall it is the AB that uses it backwards from others

this is why it is better to use PNP/NPN terminology or double check datasheets.

 

 

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I always tried to find the actual (or at least the equivalent) schematic for the PLC modules and the device to be attached to be sure and avoid terminology problems. I did this for input and output circuits.

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exactly...  :-)

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I cheat, I tell the people I hire the difference between sinking and sourcing is kind of simple.

And if they look at the machine wiring prints, follow out which wire they are switching.

PNP = It switches the positive circuit...PNP

NPN = It switches the negative circuit....NPN

I know this is simplistic, but for the non-engineers, it's easier to follow.

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