Sink/Source

[Guest Fresh]

Hi, I am very new to automation and I got some confusion about something. 1. What is the different between sink/ source? 2. What is the different between sink's input/ output and source's input/ output? I am now send for 'attachment' to a company during my 2nd year studies. I ever seen those staffs using plc to turn on the relay and they ever explained to me but not so in detail and I still got some confusion. Eg, I have a 24V dc relay with polarity. Can someone explain how to connect to the +ve and -ve of the relay from a npn sensor(eg) just like connecting +24Vdc to +ve and i/o to -ve to energize the relay and etc, etc. May I know also how is it relating to the sink/source? Can someone describes with a simple schematic diagram? Sorry for the inconvenience caused and I hope to get some explaination from you expert guys or show me some relevant websites to me as the references. Thank you very much. Regards,

[Jay Anthony 118]

Guest_Fresh: Please register at MrPLC.com and join the MRPLC.com community Register at MrPLC.com Try this discussion and then come ask questions. NPN or PNP @ MrPLC.com

[Guest]

here is something which has helped quite a few people in the past ... post on another forum and here is a picture which (I think) answers the specific questions you asked ... it says the same things as the post which Jay linked you to ... but something tells me that you might find the schematic symbols a little bit easier to understand ... in the circuit at the top, the PLC output would have to be a PNP type of output ... in the bottom circuit, the PLC output would have to be an NPN type of output ... hope this helps, Ron Edited 27 Jun 2004 by Ron Beaufort