Skip to content

ModbusRTU with EPC1522

asierasier
in PLCnext Technology & PLCnext Controls

Hello all,

I am trying to communicate an EPC1522 and an IL MOD BK DI8 DO4 PAC via ModbusRTU. For that I am using Node-Red in the EPC.

I have followed the following guide: EdgeDevices/02_ModbusToInfluxDB.md at main · PLCnext/EdgeDevices · GitHub

Once I deploy the flows, the ModbusSerial In and Out nodes seem to connect properly, but when I try to send or read a register I get the following error:

Error: {"name":"TransactionTimedOutError","message":"Timed out","errno":"ETIMEDOUT"}

I have checked the Baud Rate, parity... and seem to be okay.

Do you have any advice on how go make it work?


Thanks in advance,

Asier

Comments

  • Martin [PLCnext Technology Team]Martin [PLCnext Technology Team]

    Sorry for the very late reply.

    Here is the response from the developers

    The cause of the defect is the hardware itself.

    RS485 is supported, but limited. Only devices via 4-wire to 4-wire and a small baud-rate were able to connect when testing.

    Meaning at this time, not all devices, especially those sending messages too fast, will work.

    Communication that requires toggling the RTS line does not work with EPC for now as well.

    The UART chip on the BL2 BPC 1500 (or EPC) does not support the required switching, therefore “Auto RTS” cannot be an option in the BIOS. Which means that there must be a software solution. We do see the need of an “Auto-RTS-Toggle” and a configuration to set a baud-rate. But this can not be done via a software solution.

    The development is currently researching the solution and I can not give you an estimated time when this will be done. 

    To sum it up: At this moment, unfortunately not all Modbus devices will work and the usage of Modbus RTU is very limited (Only 4-wire to 4 wire and no devices that require a RTS toggle)

    This will be included in the description of the device unless we fixed that issue.

     

  • asierasier

    Hello Martin,

    Thanks for your answer.

    I "solved" it by using an modbus RTU to modbus TCP gateway until I could find a better option to make it work, but I guess I will just leave it like that for now.

    Best regards,

    Asier

  • asierasier

    Good morning,

    I would like to know if there has been any updates in the usage of the serial ports of the EPC1522.

    One customer would like to collect data via Modbus RTU, and I would like to know if I should advice them to use the Modbus TCP/RTU Gateway or if the serial port of the EPC can do it all by itself now.

    Thanks in advance!

  • Martin [PLCnext Technology Team]Martin [PLCnext Technology Team]

    Hi Asier, there is no change, and the earlier comments still apply.

  • asierasier

    Hi all,

    I was asked by this topic by a couple costumers and for your previous answers, the problem is the hardware of the port itself, not something software related.

    Do you know if in the future the serial port will be replaced so that it can work with 2-wired devices? Or This device will just work for 4-wired ones?

    Thanks in advance!

  • Martin [PLCnext Technology Team]Martin [PLCnext Technology Team]
    edited June 2023

    The chip that is responsible for this issue will not be replaced in these EPC devices, so they will only ever work with 4 wired devices.

Sign In or Register to comment.