Transmission protocols are sets of rules that determine how data is transmitted across communication networks. They define how devices communicate, detect errors, manage data flow, and ensure reliable delivery. Here's a breakdown of common transmission protocols, categorized by application:
🔌 1. Industrial Communication Protocols
Used in PLCs, SCADA, DCS, etc.
| Protocol | Type | Features | Common Use Case |
|---|---|---|---|
| Modbus RTU | Serial (RS-485) | Simple, widely used, master/slave model | PLC ↔ Field Devices |
| Modbus TCP | Ethernet | Faster than RTU, uses TCP/IP stack | PLC ↔ SCADA, HMI |
| Profibus | Serial | Deterministic, fast, complex addressing | Siemens PLCs, sensors, drives |
| Profinet | Ethernet | Real-time, integrates with IT systems | S7-1200/1500 PLCs, SCADA |
| CANopen | Serial (CAN) | Reliable, multi-master, time-critical applications | Automotive, robotics |
| EtherNet/IP | Ethernet | Uses standard Ethernet hardware | Allen-Bradley, Rockwell systems |
| DeviceNet | Serial (CAN) | Based on CAN, master-slave | Allen-Bradley field communication |
🌐 2. General Data Transmission Protocols
Used in networking and communication systems.
| Protocol | Layer (OSI) | Description | Use Case |
|---|---|---|---|
| TCP (Transmission Control Protocol) | Transport | Connection-oriented, reliable, error-checked | Web, FTP, Email, Modbus TCP |
| UDP (User Datagram Protocol) | Transport | Connectionless, faster, but no guarantee | Video streaming, SCADA (fast data) |
| IP (Internet Protocol) | Network | Handles addressing and routing | Backbone of internet and LANs |
| HTTP/HTTPS | Application | Web communication, encrypted in HTTPS | Browsers, REST APIs |
| FTP/SFTP | Application | File transfer protocols (S = Secure) | File sharing |
| MQTT | Application | Lightweight publish/subscribe protocol | IIoT, remote sensors |
🔒 3. Serial Communication Protocols
Often used in embedded and industrial systems.
| Protocol | Type | Features | Use Case |
|---|---|---|---|
| RS-232 | Point-to-point | Short distance, simple serial communication | PC ↔ PLC, HMI |
| RS-485 | Multi-point | Long distance, up to 32 nodes, differential pair | Modbus RTU networks |
| RS-422 | Balanced | Similar to RS-485 but mostly point-to-point | Industrial communication |
| SPI | Synchronous | High-speed, short distance, master/slave | Microcontrollers, sensors |
| I²C | Synchronous | 2-wire, multiple devices | Sensors, EEPROMs |
📶 4. Wireless Communication Protocols
Used in wireless and IoT systems.
| Protocol | Medium | Features | Use Case |
|---|---|---|---|
| Wi-Fi | Radio | High-speed, IP-based | IoT, SCADA remote access |
| Bluetooth | Radio | Short-range, low-power | HMI panels, sensors |
| LoRaWAN | Radio | Long-range, low power | Remote telemetry |
| ZigBee | Radio | Mesh networking, low data rate | Home automation, industrial IoT |
| NB-IoT | Cellular | Narrowband, designed for low-power devices | Remote sensors in industries |
Would you like a deeper explanation on any of these (like Modbus, Profinet, MQTT), or how to implement one on a specific PLC or HMI system?