Modbus RTU

Modbus RTU is an open serial protocol derived from the Master/Slave architecture that was originally developed by Modicon (now Schneider Electric). It is a widely accepted serial-level protocol due to its ease of use and reliability. Modbus RTU is commonly used within Building Management Systems (BMS) and Industrial Automation Systems (IAS).

Modbus RTU messages are a simple 16-bit structure with a CRC (Cyclic-Redundancy Check). The simplicity of these messages is to guarantee reliability. Due to this simplicity, the basic 16-bit Modbus RTU register structure can be used to pack in floating-point, tables, ASCII text, queues, and other unrelated data. This protocol primarily uses an RS-232 or RS-485 serial interface for communications.

EasyEdge Engine Features

EasyEdge Modbus RTU Engine allows you to connect devices using the Modbus protocol. EasyEdge Modbus RTU Engine operates as a Modbus master and implements two-way communication. It can connect to multiple devices even with different communication parameters

  • Supports multiple equipment via RTU;
  • Supports files descriptor (.pdf or .csv) parser (JiT Connector);
  • Supports adjustable address base (0 or 1);
  • Supports full address range (0-65535);
  • Supports HEX addressing (0-FFFF);
  • Supports word and byte swapping (byte order): 
      • MSW: Most significant word first;
      • LSW: Least significant word first;
      • MSB: Most significant byte first;
      • LSB: Least significant byte first. 
  • Supports equipment slave id full range (1-247);
  • Supports broadcast messages using slave id 0;
  • Supported functions:
      • read coil status (01);
      • read input status (02);
      • read holding registers (03);
      • read input registers (04);
      • force single coil (05);
      • preset single register (06);
      • force multiple coils (15);
      • preset multiple registers (16);
      • Exceptions;
  • Supported data types;
      • Boolean;
      • Integer8;
      • Integer16;
      • Integer32;
      • Integer64;
      • Unsigned8;
      • Unsigned16;
      • Unsigned32;
      • Unsigned64;
      • Floating Point 32;
      • Floating Point 64;
      • String;
  • Support for reading/writing data that spans multiple contiguous registers with different sizes and byte order (for example interpreting the value of four contiguous registers as a 64-bit Floating Point);
  • Adjustable polling request time per equipment;
  • Adjustable minimum request interval per register;
  • Adjustable pooling request timeout;
  • Supports automatic black list, avoiding requests for disconnected equipment;
  • Supports minimum channel silence, forcing a time between every request on the serial bus;
  • Support for least significant word (LSW) and most significant word (MSW);
  • Besides LSW/MSW, it allows big-endian/little-endian swapping on all scalar data types;
  • Allows different communication options (baud rate, byte size, parity and stop bits) on the same serial bus;
  • Inconsistent data canceling, suppressing Modbus vulnerability for out-of-time and out-of-order replies;
  • Allows Ethernet encapsulation providing communication with serial devices over Modbus TCP/IP servers

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