The Common Industrial Protocol, also known as CIP, was developed by Rockwell and is now managed by ODVA.
CIP is specially developed for industrial applications and provides a method for transmitting data, managing, connecting, and facilitating the transmission of information on the network.
The general industrial protocol allows users to integrate automation applications including control, security, synchronization and motion. It is an object-oriented protocol: devices are represented by an object model, network-specific objects define how to configure parameters, and communication objects provide a way to establish communication and access data and services from the device through the network.
Each object has attributes (data), services (commands), connections and behaviors (reactions to events) defined in the CIP object library. The object library supports many common automation equipment and functions, such as analog and digital I/O, valves, motion systems, sensors and actuators.
Therefore, if the same object is implemented in two or more devices, the behavior of the object in each device will be the same. The grouping of objects in a device is called the "object model" of the device.
The general industrial protocol also defines device types, and each device type has a device configuration file. The device configuration file specifies the CIP objects that must be implemented, the possible configuration options, and the format of the I/O data.
This means that all devices of a given type have a common application program interface. The object that defines the routing mechanism also allows messages to pass seamlessly between different CIP networks (for example, EtherNet/IP and DeviceNet).
Another key feature of CIP is that it defines two communication or message types: explicit and implicit. Explicit messages are used for "on-demand" data (information) and are transmitted via TCP (Transmission Control Protocol). Implicit messages are used to control data (input and output) (of which high speed and low latency are important), and are transmitted via UDP (User Datagram Protocol). The UDP protocol allows messages to be sent in smaller packet sizes, and the producer-consumer model can be used for these key implicit messages.
The four types of industrial networks we often talk about are sometimes called "CIP networks", including EtherNet/IP, CAN, ControlNet, and CompoNet. They all include CIP in the communication, presentation, and application layers.
EtherNet/IP implements CIP through standard Ethernet; similarly, CAN network forms the basis of DeviceNet through applied CIP; ControlNet uses CIP on the CTDMA (parallel time division multiple access) data link layer; and CompoNet uses TDMA (time division multiple access) CIP is implemented on the data link layer.
In addition to the above network series, CIP also includes other extended functions, such as CIP safety for fail-safe communication in functional safety implementation; CIP Sync, to achieve real-time synchronization between devices; CIP Motion for multi-axis distributed control in real-time Movement; CIP Energy is used to monitor and manage energy consumption to ensure optimal energy use (OEU).