Watch the full implementation on Devhead's YouTube channel and see it in action:
🔗 live Demo
- OVERVIEW
- MODBUS NETWORK EXAMPLE
- AVAILABLE STANDARDS
- MODBUS MEMORY AREAS
- CONNECTION DETAILS
- RTU FRAME FORMAT
- FUNCTION CODES
- live DEMO
- THANK YOU
- Modbus is an open standard
- Simple data representation, works in request-response command structure
- Standard transport, Modbus RTU commands are simple
- It uses RS485, a differential communication (support 32 nodes in multi-drop configuration)
- RS485 provides noise immunity better than RS232 electrical standard
- It requires very little code space, with that developing automation app possible
| Memory Area | Type | Address Range | Description |
|---|---|---|---|
| Coils | Discrete output | 00001–09999 | Valves, actuators on/off |
| Inputs | Discrete input | 10001–19999 | Switches |
| Input Registers | Analog input | 30001–39999 | Connect sensor temp, etc. |
| Holding Registers | Analog output | 40001–49999 | Control devices, VFD |
MODBUS SERIAL LINE PROTOCOL DATA UNIT (PDU)
SLAVE ADDRESS | FUNCTION CODE | DATA | CRC
1 Byte | 1 Byte | 0–252 Bytes | 2 Bytes (CRC low | CRC high)
| Function Code | Action | Table Name |
|---|---|---|
| 01 (0x01) | Read | Discrete Output Coils |
| 05 (0x05) | Write single | Discrete Output Coils |
| 15 (0x0F) | Write multiple | Discrete Output Coils |
| 02 (0x02) | Read | Discrete Input Contacts |
| 04 (0x04) | Read | Analog Input Register |
| 03 (0x03) | Read | Analog Output Holding Registers |
| 06 (0x06) | Write single | Analog Output Holding Registers |
| 16 (0x10) | Write multiple | Analog Output Holding Registers |
Watch the full implementation on Devhead's YouTube channel and see it in action:
🔗 live Demo
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