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Direct PC to PLC comm on RS232

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  • Direct PC to PLC comm on RS232

    I am ignorant in the area of PLCs, but my boss has asked me to investigate a particular remote control setup.

    The device is question is a Koyo Directlogic 06, which has an RS232 interface on it. It is attached to a commercial ice machine to run the process. As such, it has the control buttons: Eject, Blow, Auger, etc., programmed and assigned to particular coil numbers. You can use a EA1-6SML plugged into the RS232 to do that, but we need to send those commands from a PC if possible.

    Is there a way to send commands from a PC through the RS232 port to turn those coils on and off?

    Failing that, is there a small, inexpensive (or free) HMI software I can use on the PC to send these coil commands? I have 5 buttons that I need to send a 1 and a 0 to.

  • #2
    In all likelihood the HMI is not controlling the outputs directly. Instead they are controlling other information in the PLC which is interpreted by the PLC program as a request to turn the outputs on or off. Therefore for a PC program (an yes there are ways to control just like the HMI from a PC program) to do the same as the HMI program they would have to write to the same points inside the PLC.

    I take it that you don't have access to the PLC program or to programming software. Communication with the control PLC supplier would be the next step.



    • #3
      AutomationDirect Forum

      I thought I was in contact with the supplier ?

      The programmer for the PLC won't give me access to the program, but will give me the coil numbers for the buttons I need to press.


      • #4
        Actually I meant the supplier of the program. Sorry for the confusion. Good luck on that not-having-access-to-the-program stuff.



        • #5
          webpilgrim, if you want to control the ice machine DL06 PLC remotely, using serial communication to touch panel HMI or PC HMI, then yes, you would need to have access to the PLC.

          If the PLC is not password-protected, then you can gain access with DirectSOFT. If the PLC is password-protected, then you need to contact the PLC programmer, or "start from scratch" to re-design the control system.

          Are you saying you now have a touch panel (part number ?) connected to the serial port to Eject, Blow, Auger, etc? If so, you can extend the touch panel using RS232/485 adapters for remote operation (but not PC-operation).

          Are Eject, Blow, Auger, etc from hard-wired push buttons going to the DL06 digital inputs? If so, you could still get remote operation by using a second DL06 to communicate with a PC HMI (or remote touch panel HMI).


          • #6
            Thanks for input

            I captured the HMI-PLC serial communications and view it. There is a continuous conversation back and forth, so you were certainly correct on that.
            I have decided to use a RS232 over Internet solution called Vport to take in RS232 output from the HMI, encapsulate it for Internet transmission, send it through the Internet connection at the remote site, receive at the PLC site, turn it back into RS232 and send it to the PLC.

            Do you know of any timing restrictions on this type of HMI-PLC communications (i.e. do you think the slight time delay from transmitting it will mess up the communications)?

            Thanks again


            • #7
              webpilgrim, you want to disconnect the C-more micro EA1-S6ML (sorry, you did give the part number) from the DL06, and re-connect the serial link through the internet connection using Vport, correct? You then do not need a local touch panel at the ice machine for local control?

              We have not tried this configuration. But we have connected to the local C-more touch panel with standard computer, over the internet, using the Remote Access feature. Have you looked at into this feature?


              • #8
                As a note of safety. A sign should be posted at the remote site for anyone working with this machinery that it may be controlled from a remote location. They should either turn off power to the unit, put it in a safe mode (so that there is no power for outputs) or disconnect the remote communications connection.

                If the connection can act as a display conduit it can be a link for the actual programming software which can control anything.



                • #9
                  I am doubtful about this working, however it will be interesting to see if you can get it to work.

                  The one thing that I can say is that you will have to slow down the poll time tremendously and add in a much longer timeout on the communication from the HMI to get it to work.

                  A good starting point for timeout is to take the ping time + 1000ms. For your Poll delay I would start at the same number then reduce the time once it is working to get to the best possible update time. Both numbers might need to be raised from this initial value or dropped. Only real world testing will let you know for sure.
                  If you have an urgent issue, please contact AutomationDirect's Technical Support team.

         Technical Support: 1(800) 633-0405 or (770) 844-4200 Email Tech Support


                  • #10
                    Progress report

                    Thanks for the input. No I haven't seen the Remote Control feature and none of the contacts I've talked to have mentioned it even though I specifically asked about remote control from a PC. I'll be sure to look that up.

                    Have the software all set up and tried it today, but apparently the PC-PLC cable I bought from AD requires their software to operate (its a USB-RS232-RJ12 adapter), so I'll have to make a cable it looks like.

                    I realize that the programming software for the Koyo would let me do this, but the owner is not willing to go the money to equip 40 ice machines with a legal copy (and I'm not going to copy it).

                    Also, I've looked in all the menus on the EA1 control panel and I can't find serial settings anywhere. My PLC contact says 9600,8, n, 1 .. IS this correct? Also, I can't find the flow control anywhere: is it No Flow Control or Software (XON/XOFF) flow control ?

                    Thanks for your help.


                    • #11
                      Where do I find Remote Access?

                      One of the replies referenced Remote Access for the Koyo 06. I can't find it on the AD website. Can you give me a lead or contact for it, please?


                      • #12
                        Sorry to be the bearer of bad news.

                        The Cmore micro does not have the remote access feature.

                        As far as built in remote access to the DL06 without using Directsoft or some other piece of software, there isn't any. The PLC requires external software of some sort.

                        To be able to accomplish what you have mentioned with what you currently have, at a minimum you will need OPC or DDE server software. Then you still need some piece of software to display the data. This might be Excel, a Visual Basic Application, or some other piece of software. Unfortunately this is usually not an easy project.

                        The other possibility is to trade the EA1-6SML for a full featured Cmore that has an Ethernet port. This would include the Remote Access feature and mke this a fairly simple task.
                        If you have an urgent issue, please contact AutomationDirect's Technical Support team.

               Technical Support: 1(800) 633-0405 or (770) 844-4200 Email Tech Support


                        • #13
                          Remote Access for C-More panels

                          Where can I find a manual for the Remote Access for C-More panels? Searching and Googling showed me a FAQ for remote access, but no manual.

                          I assume you mean by a Ethernet-equipped C-More something like this, since none of the Micro Graphics panels seem to have a Ethernet version or Ethernet adapter: A7-S6M: 6-inch C-more grayscale STN touch panel (5.7 inch viewable screen), 15 shades of gray, 320 x 240 pixel QVGA screen resolution, 333 MHz CPU, 24 VDC (20.4-28.8 VDC operating range), NEMA 4/4X, IP-65 (when mounted correctly; for indoor use only), non-replaceable backlight, 50,000 hour half-life. Built-in Ethernet and USB; supports Compact Flash.

                          The manual for this unit does not reference Remote Access, nor does the any of the software listings on the page and 'Remote Access' in search just shows some Think n Do software.

                          So how can I find out about this?


                          • #14
                            webpilgrim, you can find out about the Remote Access feature by doing a search for Remote Access in the Help file in the C-more programming software. It is a great feature. You can also send email and transfer data files using the internet connection. You can also review the web link below.

                            Forgot to mention, this feature does not require any 3rd-party software or any software package to be installed on the remote computer. (The utility is downloaded when you connect to the C-more.)
                            Last edited by KPrice; 10-29-2009, 03:14 PM.