My Italian cousins really love soccer or as they call it “futbol” – a Spanish translation of the English word football. They’ll sit for hours watching the ball get kicked back and forth ending agonizing hours later in a 1-0 “thriller”. As you might tell, I’m not a fan. I’d rather get a prostate exam from a 6’5” 350-pound doctor who played guard for Notre Dame.
American football and soccer have their differences, but they are similar. All the basics are the same. There is a ball. There is a field. There is a goal. The core is pretty similar but everything around that core is pretty different. It occurred to me today that the same applies to PROFINET IO and EtherNet/IP. They both have very similar cores but everything around those cores is different.
- Both are open technologies with an independent trade organization that maintains the specification. The PROFINET IO specification is controlled by Profinet International while the EtherNet/IP specification is controlled by the ODVA.
- Both are controller-centric. A Programmable Controller establishes connectivity with one or more sensor/actuators. In PROFINET IO those devices are called device-side devices while in EtherNet/IP they are called EtherNet/IP Slaves.
- Both use cyclic messaging to move inputs from the end-device to the controller and outputs from the controller to the end-device though the structure of the data that is mapped is radically different.
- Both have a control file that describes how data is mapped to the controller. In EtherNet/IP that file is called an EDS or Electronic Data Sheet. In PROFINET IO, that file is called a GSDML. GSDML are General Station Description files written in XML format. Both describe the features of the device model.
- Both technologies have an acyclic mechanism for exchanging unscheduled data and requesting on-demand services from the end-devices. Controllers must be explicitly programmed to use acyclic communications with the end-devices.
- Both technologies support a set of standard services that all devices must support and some facility that allows a device designer to enable services specific to that device.
- Standard TCP/IP communications support cyclic and acyclic communications meaning that EtherNet/IP and PROFINET IO messages can run on standard Ethernet.
- Standard controller interfaces make it easy to use these technologies with controllers. PROFINET IO easily integrates with Siemens S7 programmable controllers while EtherNet/IP devices can be easily integrated with Allen-Bradley ControlLogix.
- Device classes are identical, but the terminology varies between the two technologies. EtherNet/IP classifies devices as Scanners (controllers) and Adapters (end-devices). PROFINET IO uses the terms controller-side and device-side devices.
- Both map incoming process data (input data) directly into the input data table of the controller where it can be acted upon by the controller logic and used to create outgoing process data (outputs).
- Devices supporting either technology maintain identity data that provides information like the name of the vendor that created the device, the device type, it’s address, a product family information, catalog number and more.
The devotees of American football and soccer are, of course, more passionate than the devotees of PROFINET IO and EtherNet/IP. Even though there are parallels between the two sports and the two technologies, don’t ever expect them to merge. Soccer fans will watch soccer, football fans will watch football, Allen-Bradley customers will use EtherNet/IP and Siemens customers will use PROFINET IO. As for me, I’ll use what works – just don’t ask me to watch soccer.