🤖Have you ever tried Chat.M5Stack.com before asking??😎
    M5Stack Community
    • Categories
    • Recent
    • Tags
    • Popular
    • Users
    • Groups
    • Search
    • Register
    • Login

    PLC Module

    Bases
    5
    14
    29.6k
    Loading More Posts
    • Oldest to Newest
    • Newest to Oldest
    • Most Votes
    Reply
    • Reply as topic
    Log in to reply
    This topic has been deleted. Only users with topic management privileges can see it.
    • M
      mkellner
      last edited by

      I am converting a project from a raw esp32 module/MAX 485 driver -> modbus to M5Stack/PLC module.

      Does the PLC module supply power to the CPU from the 24V input?

      Is there an RTS Control line for the RS485 converter or is RTS Control automatic?

      (RTS Control is a method with which the RS232 device (typically a PC) tells an RS232-RS485 converter when it should enable its RS485 driver, i.e. when it should be transmitting. http://www.kksystems.com/rtscontrol )

      Is there a chip specification for the 485 converter? Which is used?

      M O malbroM 3 Replies Last reply Reply Quote 0
      • M
        mkellner @mkellner
        last edited by

        Looks like the 485 driver is a Exar SP3485.
        Some vendor on Alibaba claims it is max3485esa replacement.

        https://datasheet4u.com/datasheet-pdf-file/1103288/Exar/SP3485/1

        The SP3485 chip has
        Pin 1 - RO - Receiver output
        Pin 2 - RE - Receiver Output Enable Active LOW
        Pin 3 - DE - Driver Output Enable Active HIGH
        Pin 4 - DI - Driver Input
        Pin 5 - GND - Ground Connection
        Pin 6 - A - Non-Inverting Driver Output/Receiver Input
        Pin 7 - B - Inverting Driver Output/Receiver Input
        Pin 8 - Vcc - Positive Supply

        What pin is DE - Driver enable?

        Pin 1 - RO -> G16
        Pin 2 - RE -> ???
        Pin 3 - DE -> ???
        Pin 4 - DI -> G17
        Pin 5 - GND -> (output port G)
        Pin 6 - A -> (output port A)
        Pin 7 - B -> (output port B)
        Pin 8 - Vcc - 5V (?)

        Is there a schematic for the little module?

        alt text

        1 Reply Last reply Reply Quote 0
        • M
          mkellner
          last edited by

          I note that the vendor on Amazon is responsive, but not very technical or knowledgeble about the PLC module.

          Gave me the schematic for the M5 Core, not the PLC module.

          They suggested the ILI9341 (display) RST pin is what I was looking for. No. That's not quite right.

          1 Reply Last reply Reply Quote 0
          • M
            mkellner
            last edited by

            I'm waiting for a response supplier via vendor, who assures me that the supplier says it should work as it is and that I don't need RTS. I pointed out that the ESP-IDF documentation for UART indicates that RS485 Half Duplex requires a RTS pin (https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/peripherals/uart.html):

            0_1535921034241_esp-idf-uart-snip.png

            0_1535920297908_PLCModuleModule.png
            0_1535920306839_exar-sp3485-pinout.png

            I think I'm going to have to tie a wire between the DE pin on the 3485 to a free GPIO to get the functionality I need.

            Hopefully the supplier will eventually provide some official documentation or schematics. I suspect that this might be what you get.

            Is anyone from M5Stack here?

            O 1 Reply Last reply Reply Quote 0
            • O
              osmar @mkellner
              last edited by

              @mkellner Automatic control of RS485 transceiver data

              1 Reply Last reply Reply Quote 0
              • O
                osmar
                last edited by

                0_1535952200325_1535952159(1).png

                O 1 Reply Last reply Reply Quote 0
                • O
                  osmar @osmar
                  last edited by

                  This post is deleted!
                  1 Reply Last reply Reply Quote 0
                  • O
                    osmar @mkellner
                    last edited by

                    @mkellner Please refer to this schematic diagram.

                    M 1 Reply Last reply Reply Quote 0
                    • M
                      mkellner @osmar
                      last edited by

                      @osmar 在 PLC Module 中说：

                      @mkellner Please refer to this schematic diagram.

                      Thank you for responding!

                      1 Reply Last reply Reply Quote 0
                      • malbroM
                        malbro @mkellner
                        last edited by malbro

                        @mkellner
                        Yes the two power pins can supply the complete module, I am using 12V for the ones I have which will also power a LoRa module.
                        As already answered yes it is automatic, just transmit the data and it is sent out, I am using a Modbus protocol based on one of the Arduino Libraries but it needed a lot of changing to make it compatible with the M5Stack. Works with some Smart Meters I am working with running on the second core of the ESP32 with WiFi and Screen handling on the main Arduino core.

                        You need to make sure you connect all ten connections between the sub board and the main board, there were no instructions with my units so I had to figure them all out. A, B, C and D next to the connector, 5V and GND to the top left of the connector, Vin T2 and R2 on the left side of the main M5Stack connector and if you want to use the current measurement you need to connect pin34 on the right hand side of the main connector. I found the easiest way was to use 0.1" pitch pins and solder them to the small board first and then the main board.

                        The current measurement is done by the other chip on the small board, it appears to be the current flow into the whole system if the unit is powered from the external power connections marked 24V and G

                        K 1 Reply Last reply Reply Quote 0
                        • K
                          kittikoon @malbro
                          last edited by

                          @malbro Would you please explain what needs to be changed in Modbus protocol Library to make it compatible with M5Stack?

                          F 1 Reply Last reply Reply Quote 0
                          • F
                            franzhoepfinger @kittikoon
                            last edited by

                            @kittikoon
                            true:

                            with ESP-IDF
                            https://github.com/espressif/esp-idf/tree/master/examples/peripherals/uart/uart_echo_rs485
                            the RS-485 Demos not fit to ALL your Boards with RS-485.

                            Thanks,
                            Franz

                            F 1 Reply Last reply Reply Quote 0
                            • F
                              franzhoepfinger @franzhoepfinger
                              last edited by

                              @franzhoepfinger

                              https://github.com/espressif/esp-idf/issues/13989

                              here some BG Info.

                              F 1 Reply Last reply Reply Quote 0
                              • F
                                franzhoepfinger @franzhoepfinger
                                last edited by

                                @franzhoepfinger https://github.com/Fliegl-Agrartechnik-GmbH/M5_COMMS
                                here some PCBs for test.

                                will post results there.

                                1 Reply Last reply Reply Quote 0
                                • First post
                                  Last post