6 Replies Latest reply on Jan 28, 2014 1:05 AM by schicksal

    Industrial light sensor on PIFACE

    schicksal

      hHi,

       

      I am a real beginner with the PiFace. I have a glue about Software, but not about Hardware so far. I wanted to connect via PIFACE the digital Output contacts of a industrial light sensor (12 V DC ) to the PIFACE. Has anyone experience how to do this? Thanks upfront for the Support.

       

      KR

        • Re: Industrial light sensor on PIFACE
          iagorubio

          Can you post a link to the device ?

           

          12 V DC is somewhat vague. I guess it's the voltage required by the device, but it can be a digital 12V output on a light threshold to drive a relay, or and analog 12V output pin to read the light, that makes little sense but industrial devices are somewhat different, and I know Omron and Durus make PLCs with 12V inputs so it may be a sensor capable of driving one of those PLCs.

           

          A link to the device or its name, and what you want to do with it can help us to know your needs.

            • Re: Industrial light sensor on PIFACE
              schicksal

              Thanks a lot for your reply and your help.

              This is the product:

               

              Lichttaster mit Timer Idec SA1U-D01MWT Lichttaster mit Timer Reichweite 1 m

               

               

               

              Mit freundlichen Grüssen / Best regards

               

              Michael Fatum

               

              +49 151 54 44  30 62

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              Am 24.01.2014 um 18:55 schrieb iagorubio <messages@element14.com>:

               

               

               

              Industrial light sensor on PIFACE

              created by Iago Rubio in Raspberry Pi - View the full discussion

              Can you post a link to the device ?

               

               

               

              12 V DC is somewhat vague. I guess it's the voltage required by the device, but it can be a digital 12V output on a light threshold to drive a relay, or and analog 12V output pin to read the light, that makes little sense but industrial devices are somewhat different, and I know Omron and Durus make PLCs with 12V inputs so it must be a sensor capable of driving one of those PLCs.

               

               

               

              A link to the device or its name, and what you want to do with it can help us to know your needs.

               

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            • Re: Industrial light sensor on PIFACE
              iagorubio

              I have found that documentation that show your sensor is the "With Time delay, diffuse light" sensor type.

              http://www.idec.com/language/english/datasheet/SA1U_datasheet.pdf

               

              It's labeled SA1U-D01MT on the docs.

               

              Take into account "diffuse light" sensors may be proximity sensors that works on reflection of light emmited so it may not be a "light" sensor at all http://www.balluff.com/balluff/MUS/en/products/Diffuse-sensors.jsp

               

              You should first check what kind of sensor is yours, to know if it works on light emmited from a external source - light sensor - or the reflection of light emmited by itself - proximity / pressence / fill sensor.

               

              From what it's seen on docs, it have a couple of output types, transistor - NPN and PNP - and relay. The transistor is the row with 2 screws where the "TIme delay" knob is, and the relay it's the row with 3 screws where that knob is.

               

              It also have a selector with different operation modes near those screws - search for "Operation Chart" on the documentation for its meaning. I would put it on 0 - zero - that's "Light ON - Normal Mode" - there are One shot and delay modes as well - so you know the sensor will be "on" when it detects light, with no delays, and no special functions.

               

              The easier way to use it I guess it will be with the relay - three screws - if timing - and I am talking on the ms mark - is not important to you.

               

              If you have a multimeter - they are cheap and if you want to fiddle with electronics you will need one - you can check the continuity - electrical connection - in the relay pins. Search for "Terminal Arrangement" on the documentation  to see a graphic with the relay terminals numbered.

               

              There should be continuity on pins 5 and 4 with the sensor disconnected and no continuity on pins 4 and 3. Look for "Output Circuit / Connection Diagram" on the documentation for an explanation on the internal connection of the output terminals-

               

              When powered up, if it detects light pins 4 and 3 will be connected. If not they will be disconnected. Pins 5 and 4 will have the opposite output - connection on light off, disconnection on light on.

               

              The first ting I would do is to power up the device and check the voltage on the 3, 4 and 5 screws. It must be 0V. After that put the multimeter on continuity mode and "turn on" the light - or put something close to it. There must be continuity on pins 4 and 3. Check voltage again must be 0V. "Turn off" the light - or get something far from it - there must be no continuity on pins 4 and 3.

               

              If all this works as intended, connect the 0V terminal from your PiFace to screw 4 on the sensor , connect screw 3 to one of the PiFace input pins. Remember, if you connect 5V instead of 0V your Pi could be in danger. Check with extra care this step. The PiFace detects a connection to ground that's why we connect ground - 0V - to the sensor's relay, and back to the input pin. That way we will connect the PiFace input pin to ground when light is on, and it will be detected by your PiFace.

               

              Recheck that everything is as I said and the models on the docs and yours are the same.

               

              I downloaded the docs from here http://www.newark.com/idec/sa1u-d01mwt/sensor-photo-diffuse-1m/dp/46T9538 check that model is yours.

               

              Take your time and recheck all steps, it's important to check the voltage in the relay pins, if there is voltage the device may be faulty and I would not connect my Pi to it. In the other hand, the device is much more expensive than a Pi so may be for you to repurpose it is worth a fried Pi.

               

              Anyway, go ahead at your own risk.

               

              Hope this helps.

               

              Notes:

              In this text "pin", and "terminal" mean the connection screws to make electrical contact on the PiFace and the sensor.

               

              More info on time delay funcions for the "Operation Chart" meaning http://www.macromatic.com/blog/understanding-time-delay-relay-functions/

              More on multimeters http://en.wikipedia.org/wiki/Multimeter

              What is continuity http://en.wikipedia.org/wiki/Continuity_test

              More on relays http://en.wikipedia.org/wiki/Relay

              • Re: Industrial light sensor on PIFACE
                dougw

                Hi KR,

                You should be able to use the open collector output on terminal 4 connected like this...

                 

                PiFace.PNG

                 

                The PiFace input has the option of switching in a pull-up resistor - this option should be used since the open collector acts like a switch to ground and the resistor is needed to pull the input high when the switch is open.

                 

                Doug