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  1. Modbus: The Original Industrial Fieldbus Protocol

    Sep 2, 2025 · This article introduces Modbus, an industrial protocol that laid the foundation for fieldbus communication in industrial systems.

  2. Choosing an Interface: Why Modbus is Still Around After 40 Years

    Mar 19, 2021 · Learn about the advantages of Modbus over newer protocols when choosing an interface with third-party devices.

  3. How-To: Building a PLC Project with Modbus Communication

    Apr 5, 2022 · Modbus is a communication protocol stemming from the early days of Modicon PLCs, but is still common today. These two example implementations of Modbus transactions …

  4. Modbus TCP - What is the correct usage of Unit ID?

    Jan 26, 2012 · The unit ID is used when dealing with Modbus Bridges. Typical bridges convert Modbus TCP to Modbus serial or Modbus plus. The Unit ID is either the device Id of serial …

  5. Modbus over Ethernet | Automation & Control Engineering Forum

    Jun 25, 2008 · Modbus is a protocol. You can use Modbus protocol over Ethernet, it is then called Modbus TCP/IP. Commonly used by Schneider Electric, as Schneider bought the company …

  6. Communication problems , modbus timeout error

    Aug 14, 2020 · Modbus slave never have a slave node address zero, by definition. If you have more one slave, wire and connect to only one slave initially to get comm up and running.

  7. Modbus Exception Code 04 | Automation & Control Engineering …

    Aug 3, 2007 · I try to communicate CP341 with modbus rtu slave but the response at the funcion code 05 or 15 is always exception code 04. what kind of error is this?? anybody know ???

  8. Modbus RTU illegal data address - Control.com

    Sep 5, 2018 · I have 2 PLC controllers and in one controller I have Mapped variables to address 400001, 400002, 400004 and 400005 respectively and 400003 is not mapped. From Master if …

  9. Modbus Receive Timeout Error | Automation & Control …

    Nov 2, 2017 · Hi, I am new to Modbus. Right now I am trying to communicate and read registers from PM5100 Schneider Digital Meter via USB485B (USB to RS485 Converter)...

  10. Timeout error | Automation & Control Engineering Forum

    Feb 10, 2025 · Modbus Poll is a Modbus master simulator. If your ESP32 is indeed a master, then this won't work, as a Modbus master cannot communicate to another Modbus master.