Home› AMX User Forum› AMX Technical Discussion

Help! Modbus TCP.

nickmvnickmv Posts: 6
in AMX Technical Discussion
Hello! Do you now, is it possible to connect AMX with Modbus TCP or RTU device? Please Help me...

Comments

  • Jurgen SachsJurgen Sachs Posts: 33
    Yes it is possible to connect the NetLinx to an ModBUS Device.
    But Modbus is the protocol. It does not specify the transport.
    We did it already for Ethernet and RS485. And there are other transports possible !

    Also AMX has a module for modbus. Never tried that, since we had our own.
    Search for "Modbus" as manufacturer.

    You can get some informations and the protocols on
    http://www.modbus.org/

    But without of the understanding of modbus, it will be hard to make it :-)

    But it is possible and we made it several times
  • nickmvnickmv Posts: 6
    Thank you!
    Were i can find this modul for Modbus? (I have AMX ID)
  • Jurgen SachsJurgen Sachs Posts: 33
    On the AMX Page goto TechCenter -> "Search Third Party Devices".
    Enter "ModBus" as Manufacturer.
    You will get one hit.
    I reccomend to read also the documentation on "www.modbus.org" to understand the basics of modbus.

    Have fun
  • OceanicOceanic Posts: 5
    I am also after a ModBus TCP AMX module. Unfortunately the COMM module available on the AMX site is for serial control only, as it is a token file I am unable to alter it for TCP control.

    Does anyone know if an IP module exists or where I can get the source code for the COMM module from?

    Thanks
  • thomas.judthomas.jud Posts: 44
    I have an .AXI example...
    Thats a remote control for digital I/O contacts over MODBUS.
    // comments are in german.....

    propably a helpfile for you

    enjoy

    Thomas
  • Jurgen SachsJurgen Sachs Posts: 33
    Be aware when programming for MODBus, that you can get an "Exception" every time. I did a lot of MODBus staff and was suprised how different a protokoll can be implemented by a manufacturer.
    If you get an exception, display it. Most of the time this is a sign for an parameter out of bounds.

    The Problem is, that I can not send out the code for the module, either IP or Serial.
    Our module does the folowing:
    - Handling of the Bus. On RS485 send and wait for responce, repeat 2 times if no responce is received. On ethernet add header and make shure the packet comes though :-)
    - Calculating and adding checksumm to the outgoing packet
    - Checking checksum on incomming packet and generate error messages if not
    - we pass the "raw" mod-bus command to the module and get a raw mod-bus command back.
    - all commands are passed to a send queue and send out one by one

    So it is easy to use it in multiple installations.
    But as I sayed previous, I can not publish the code (property of our customer).
    But maybe it helps to build up your module.

    By the way in the include file provided in the posting before. If the IP connection break, it is not established again. But should be fairly easy to implement based on his code.

    Regards
    Juergen Sachs
  • OceanicOceanic Posts: 5
    Thanks very much for your feedback and code example, this will be a great help
  • Miri BlankMiri Blank Posts: 3
    Modbus through tcp/ip

    Hello Thomas,

    I tried this code with a Rokonet alarm system but without success.
    The client was opened and the questions were asked, but there was no reply.

    Do you have any idea why?

    Do you have any examples of the strings for read registers/ write registers?

    Thank you,

    Shira
Sign In or Register to comment.