I want to use serial modbus. (Modbus RTU or ASCII) but I want to communicate with 400 device with modbus rtu. How is this possible?

  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can post and accept your own answer. – Ron Maupin Dec 17 '20 at 17:28

Modbus is based on RS-485 and limited to 254 devices on a single data link (I'd advise to use considerably less), so you'll need multiple busses.

  • Is it bound by slave id? or physical layer ? Can it happen if a device like repeater is added? – gogogo May 15 '20 at 6:08
  • You need multiple busses with independent addressing. Boosting the physical layer doesn't help. – Zac67 May 15 '20 at 6:19

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