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  • #16
    Bert,

    The white thing is actually the relay. The blue thing is a socket that provides breakout connections. The specs on the 24V coil do not show a diode. The coil only requires 7ma to operate. We would put diodes on them. Not sure what the LED's are across but they appear to be part of the socket.

    Not sure what kind of motor you are running but you might need to provide some suppression for it. Also go through your wiring and make sure you don't have a ground loop. EMI can couple a lot of noise into things with a ground loop.

    Good luck on this. These are some of the worst problems we face in the industrial control field.

    Comment


    • #17
      James,

      There is no extra information on the cable about which kind of shielding. I tried measured the diameter of the wires, it's around 0,5mm, so I gues 24 AWG?

      Image below:

      Click image for larger version

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      Thank you,

      Kind regards,
      Bert
      www.forestplus.be

      Comment


      • #18
        Ok, so I've caged the Arduino and the screen:

        Click image for larger version

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        I've also changed the foilded cable to a better one (although I think it's a better one.): Its a FTP 4PR 23AWG CAT6 cable, grounded at one end.

        It looks like it's improved, I can use the motors a little bit longer (4-8s) and then it's unsynced (the button to switch forms doesn't work anymore).

        I also had a couple of times that the motor didn't stop when I lift my finger of the button. Like that the "release button" command didn't came through to the arduino.

        Thank you,
        Bert
        Attached Files
        Last edited by Bertf; 23 June 2015, 03:26 PM.
        www.forestplus.be

        Comment


        • #19
          Hi Bert

          Sometimes your pictures dont show up in your posts - not sure how you are doing it exactly. One way is to click the A on the top right, click on the 'Image' tool, select the file from your PC under the Upload tab, and send it to the server. You then have to wait for the box to disappear, which will happen when it has uploaded it. May you click close or something before its fully uploaded it?

          Anyway...

          I think from this point, you really need to get a scope, so you can try and see what is actually going on.
          Guessing, as we have been doing up till now, only gets you so far. Need to get some facts about the kind of noise in the system, and what could be causing the problems.

          Do you have a scope available, one you can beg/steal/borrow from someone, and try and see what the signals are like when the motors are off, compared to what they are like when the motors are on?

          Regards
          James

          Comment


          • #20
            Originally posted by ccsial View Post
            Bert,

            The white thing is actually the relay. The blue thing is a socket that provides breakout connections. The specs on the 24V coil do not show a diode. The coil only requires 7ma to operate. We would put diodes on them. Not sure what the LED's are across but they appear to be part of the socket.

            Not sure what kind of motor you are running but you might need to provide some suppression for it. Also go through your wiring and make sure you don't have a ground loop. EMI can couple a lot of noise into things with a ground loop.

            Good luck on this. These are some of the worst problems we face in the industrial control field.
            Ccsial,

            You think it could be the 1st level relays? They're controlled with 24VDC from the universal controller and they operate a 24VAC circuit that controls the 4 pole contactors. These 4 Pole contactors switch the 3 phase 220V motors.

            When I cut off the power on the 220V phases with the safety switch and do the test again, then everything works fine. The screen and the arduino don't unsync, the 24VDC-24VAC relays work perfect, also the contactors close like they're supposed to. (but because there's no power over the contactor poles, the motors don't spin ofcourse)

            This makes me think the problem lies somewhere with the contactors, the 220V,... Or am I wrong here?


            Thank you,

            Kind regards,
            Bert


            www.forestplus.be

            Comment


            • #21
              I'm sure the motor is the problem. Make sure the motor wiring is as far as possible from the other wiring and try to cross at 90 degrees. You could also try some RC snubbers across the motor itself.

              One other thing you could try is to unbolt the display from the enclosure and leave it float. I have seen ground loops caused by non isolated mounting. The current spikes through the display frame could cause the 4D cpu some issues. I'm assuming it is not already isolated.

              Comment


              • #22
                Hi,

                I've borrowed an oscilloscope and these are the results. I don't see much intererence on the TX and RX lines between the arduino and the screen.

                I've also tested around the coil of my first level relays. The image below shows the disturbance when shutting the loop down:
                Click image for larger version

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                To try to solve this, I added a diode (1N4007) over the coil like on the scheme below. (Is this what you mentioned early ccsial?)



                It looks like it's better but the display still gets unsynced.

                Click image for larger version

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                I'd like to remark that the display and arduino unsync when motors start up or shut down. Doesn't matter how long the motor runs, I haven't found it getting unsynced by just letting the motors run.

                I've ordered Solid State Relays (Finder 34.81.7.024.8240) to replace these mechanical ones (Finder 34.51.7.024.0010) in the hope this will help.

                I've also ordered some RC snubbers, but how do you mean place them across the motor itself? Over the phases at the motor?

                The 4D screen is now "floating" in a wooden panel but this didn't solve it.

                Are there any other test I have to do with the oscilloscope?

                Thank you.

                Kind regards,
                Bert
                www.forestplus.be

                Comment


                • #23
                  If you use the solid state relays you should not need snubbers since they should turn on and off a zero crossing. I would hope that solves this issue.

                  The snubbers can go over the motor phases. They absorb dvdt. But again, with SSR no need for them.
                  Last edited by ccsial; 24 June 2015, 10:50 PM.

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                  • #24
                    The RC snubbers seem to have done the trick :D. I've placed them accros the contactor over every phase.

                    Thank you both for all the support!
                    www.forestplus.be

                    Comment


                    • #25
                      Great news Bert.

                      Comment


                      • #26
                        Ccsial and James,

                        Thank you very mucht for the support! The project is finished and it works like a charm!
                        I've uploaden a video below with the end result:



                        The working proof that you don't need expensive PLC systems

                        Up to the next project!
                        www.forestplus.be

                        Comment


                        • #27
                          Nice work, and very glad you got the system working.

                          What is the machine exactly - what does it do?

                          Many thanks for posting the video.

                          Regards
                          James

                          Comment


                          • #28
                            reserved, i will need this post

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