Industrial Communication Protocols

PROFINET

• Fast deterministic data exchange between controllers like programmable logic controllers (PLC) and cell zone devices including I/O blocks, sensors, drives and instruments.
• Time-sensitive and reliable data delivery.
• Delivers data at highly precise intervals without variance.
• Delivers data within tight time margins of 1 millisecond (ms) or less.
• de facto European industrial Ethernet standard.

Modbus

• Industrial communication protocol developed in 1979.
• Runs over serial links, TCP/IP, and UDP networks.
• Uses a request-response model with a primary-subordinate relationship. Communication occurs in pairs - a primary device initiates a request, then waits for the subordinate’s response.
• Central primary device can become a bottleneck in large systems.

Ethernet/IP (EIP)

• Provides real-time communication for automation applications over standard Ethernet networks.
• Classifies nodes into device types with predefined behaviors based on the Control and Information Protocol (CIP) used in Devicenet and ControlNet.
• EIP enables seamless connectivity from sensors to controllers to enterprise networks.
• de facto North American industrial Ethernet standard.

CC-Link

• Connects devices from different manufacturers into a fast, reliable control system.
• High-speed communication rate of 10 Mbps, up to 100 meters, and supports up to 64 connected devices.

Common Industrial Protocol (CIP)

• CIP models network devices as a collection of objects, where each object groups related data values called attributes.
• CIP only specifies the object attributes to expose, not their implementation.
• Media independent industrial protocol for automation applications.

DeviceNet

• Used to connect a PLC to simpler devices.
• Provides power on its communication lines.
• Type of CAN (Controller Area Network).

EtherCAT

• IEC international standard.
• Focused on short cycle times (≤ 100 microseconds [µs])
• Operates in a deterministic ring topology.

RS Serial Protocols

• RS-232 - commonly found on older computers to connect peripherals, restricted to point-to-point and cable length.
• RS-422 - higher data rates and longer distances, up to ten devices.
• RS-485 - supports multi-point network with multiple devices.