PROFINET vs EtherNet/IP: The Similarities and Differences
PROFINET and EtherNet/IP are currently the most popular Industrial Ethernet protocols in automated industrial environments. So why choose one protocol over the other? After all, both offer real-time communication, use the same Ethernet technology and they can even operate on the same physical network.
Let’s compare these two platforms to see how distinctive they really are. We’ll start by giving a brief introduction to both, then we’ll move on to their similarities and differences.
What is PROFINET?
Like PROFIBUS, the classic fieldbus solution first introduced in 1989, PROFINET was developed by a team of major automation companies and several German institutes, and it is managed by the PROFIBUS & PROFINET International group (PI).
PROFINET is an application, so it sits on Layer 7 (application layer) of the OSI model delivering data through several communication channels. For non-time-critical tasks such as configuration and parameterization, it can use TCP/IP or UDP/IP communication. But for time-critical tasks like RT, IRT or TSN, it skips this and communicates directly through the Ethernet layer instead.
Introduced in the early 2000s as an open standard, PROFINET is a full duplex system and runs at high transmission speeds. It sends I/O data between controllers and devices in standard Ethernet frames, whose sequence is prioritized by a virtual local area network (VLAN). Because these frames have little overhead, the deviation of the cycle time, or jitter, is low.
Identification is mainly done using device names that comprise letters and numbers, and IP addresses are assigned automatically.
What is EtherNet/IP?
EtherNet/IP was developed by ControlNet International (CI) and Open DeviceNet Vendors Association (ODVA). Introduced in the early 2000s and now managed by ODVA, Ethernet/IP is based on the Common Industrial Protocol (CIP).
Like PROFINET, EtherNet/IP sits at the application layer and is backed by defined standards and extensive communities. Unlike PROFINET, it transfers data to the network via the TCP/IP and/or UDP/IP layers. These packages of data are packed and unpacked, and headers and info are added and deleted as they move through the layers.
Two types of messages are carried by EtherNet/IP: “Implicit” messages for sending I/O data and “Explicit” messages for configuration and diagnostics. Implicit messages are sent from pre-set memory locations to a controller through a UDP port at prescheduled intervals. Explicit messages are sent to a client through a TCP port in response to a specific request for that data.
Identification of EtherNet/IP devices is done through IP addresses.
The similarities between PROFINET and EtherNet/IP
Both PROFINET and EtherNet/IP offer real-time communication and both use the same Ethernet technology. They can even operate on the same physical network. Here are several more similarities:
- Cycle times can be set for each device individually.
- Switches are used to make several types of topologies.
- Ring topologies for redundancy are supported.
- The typical cycle time is 10ms.
- The typical baudrate is 100Mbit with CAT5, 4-wire cabling and RJ45 connections.
- They can work alongside other Ethernet devices in the same network.
- The maximum number of nodes depends on the subnet of the IP addressing.
The similarities are many because, as PROFIBUS & PROFINET International (PI) says, these are “complementing technologies, not competing technologies”.
The differences between PROFINET and EtherNet/IP
Both of these protocols are used for high-speed, real-time and deterministic communication in many types of automated settings, including process manufacturing plants, distribution centres and airports. However, there are key differences:
- Industry acceptance: PROFINET is most popular in Europe, while EtherNet/IP is more favoured in the USA. There is no significant difference in popularity across Asia.
- Precision: EtherNet/IP utilizes UDP/IP for data exchange and PROFINET sends its data directly to an Ethernet frame, eliminating differing and fluctuating transmission delay times. For this reason, PROFINET has a more precise cycle time.
- Components: Like other technologies that are associated with the ODVA, Ethernet/IP uses CIP to manage IO data for network communications. This means it can use off-the-shelf hardware. PROFINET, on the other hand, can require components that are specified by the controller’s vendor.
Is one better than the other? Not really. Your choice is just as likely to be determined by geography and existing systems as it is cost and speed. But at least you now know what sets them apart.
For more information about PROFINET & EtherNet/IP and customized advice for your network design, request a FREE online consultation with one of our experts!
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