Suril

MrPLC Member
  • Content count

    4
  • Joined

  • Last visited

Community Reputation

0 Neutral

About Suril

  • Rank
    Hi, I am New!

Profile Information

  • Country Australia
  1. Sorry, but I am still confused with the concept of sourcing and sinking. I believe that the PLC card being positively switched and have reference as 0Vdc means it is a "sinking" input card and hence you are suggesting to use a sensor with PNP (sourcing) transistor output.
  2. The PLC input card we have is positive switching and the reference ground for all points is 0V power contact.
  3. Hello all, I am going to do some tests on various devices controlled by a PLC. I was trying to make a test board for the PLC including a few switiches, LEDs for digital input and output. Is such a test board or kit available in the market? If not, how do i go ahead and make one. Any suggestions please. Also to test the analog inputs I need a signal generator to generate 4-20mA and 0-10V signals. Please suggest a medium ranged signal generator. Thanks.
  4. Hello all, I am working on a project where my company is contracted to design, install and commission traffic management control system. We are going to install Overheight Detectors to detect vehicles above certain height. The overheight detection is monitored and controlled through a PLC. The signal output from the receiver of the overheight detector pair is the input to the PLC digital input card. I am supposed to choose the type of overheight detector (sensors) based on the output. The two options are: 1. NPN transistor output, and 2. PNP transistor output. Researching from the web, I was able to know that NPN is a "sinking" device and PNP is "sourcing". The logic of detection is that when the overheight detectors are in normal state the input to PLC is "HIGH" and when the overheight vehicle is detected the input to PLC goes"LOW". The PLC card is a sinking input card. The dilemma is the selection of the sensors from the above mentioned outputs. I am also a bit unclear on the concept of sinking and sourcing from the perspective of field devices as well as PLC I/O cards. If someone could please explain this??? Can I select a sensor with NPN transistor output and connect it to the PLC input card to obtain the desired input signal? If yes, how will this work? Could anyone please suggest what type of sensor do I need and why would that type of sensor be suitable in regards to sinking and sourcing as well as the control logic? Thanks.