Can multiple Modbus TCP Masters be added to a port?

2015-12-14
2015-12-18
  • danielcliffe - 2015-12-14

    Hello everyone,

    I am trying to determine whether I can add multiple Modbus TCP masters to a single Ethernet device in the Device Tree and, more specifically, will I actually be able to communicate through all of them?

    The reason I need to use multiple masters is because each Modbus TCP master can only have 32 slaves, but I need to communicate with several hundred devices. I also noticed that Device IDs only go up to 247, and am not sure if this is important.

    I am also wondering if I have just gone about this in the wrong way. Any advice is appreciated.

    Thank you!

     
  • danielcliffe - 2015-12-15

    I found a couple of Modbus slave devices around the office and tried it out. It works fine with two masters and one slave apiece going through the same physical port. Unless there is some bizarre limit that I need to have 32 devices to see, I would say there is no hard limit on the number of Modbus slaves in CODESYS.

     
  • stef - 2015-12-18

    Hello danielcliffe,

    As I read your post two days ago I just tried to find out how many Modbus Masters can be added to the Ethernet-device.
    Codesys allows to add 10 Masters, when this number is reached the button "Add Device" in Dialog "Add Device" will be greyed.
    I also tried to find out how many Slaves can be added to those masters. Codesys limits to 32 Slaves for each master, so you can theoretically communicate with 320 Slaves.
    Please Note: I just have Codesys Software but no Control System. So the Information ist only theory. You should try to find out, if such a configuration works in a life system.

    I hope this helps.

    Regards,
    stef

     

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