My wife and I are very similar people in a lot of ways but also dissimilar in other ways. One specific aspect in which we could not be any more different is our taste in food. At work, I often like to pick up food from one of my favorite nearby taco joints. A typical order includes three or four tacos containing lengua (beef tongue) or buche (pork stomach). Sure, it sounds nasty, but it is delicious, especially covered in hot sauce. My wife’s taste could not be any different. Her diet primarily consists of chicken tenders, cheese curds (a Wisconsin delicacy for you folks outside of the midwest), French fries, pancakes and pasta. Frankly, I eat like a caveman and she eats like a toddler. Finding joints for dinner dates could not be any more challenging, until recently when we found a hidden gem near our apartment called Kick Switch. This place has saved me many a headache: it has a little bit of everything, which is great for my wife and me.
EtherCAT is to control engineers as Kick Switch is to our date nights. It just makes everything a lot simpler. EtherCAT is a super-flexible Ethernet network that is capable of “processing on the fly.” What this means is that messages are passed to the next node in the ring before being processed by the node, which allows the network to operate with amazing speed and efficiency. EtherCAT offers more features beyond just speed and efficiency, which make it one of my favorite industrial protocols. Here are my three favorite aspects of EtherCAT.
#1 Flexible Topology
EtherCAT creates the possibility of a fieldbus system using Ethernet hardware. Combining the fieldbus trunk lines and individual branches gives you flexibility in programming for an EtherCAT network. It also has built-in redundancy that compensates for potential breaks in wiring. Should a line break, the network can detect it and the EtherCAT frame can travel to the end of the network and, because messages travel back over the same path in reverse, the frame reverses, and travels back to the master. In this way, all EtherCAT networks can act as though they’re in a ring topology.
I’m a cheapskate, which is part of the reason I like EtherCAT. Hardware costs for the controller or master device are limited as no special hardware is required and any Ethernet-enabled PC can be used as a master device. EtherCAT slave devices require a fairly large investment in design and development as the EtherCAT ASIC is a large footprint device that is more expensive than standard Ethernet-enabled microprocessors. On system implementation, EtherCAT can be very cost effective. No additional switches, routers or hubs are required to form the EtherCAT network, and it can be deployed in the topology that is most suitable for the application.
#3 Device Profiles
EtherCAT uses device profiles similar to the way EtherNet/IP and other CIP protocols use objects. Many Fieldbus devices used in EtherCAT networks are already defined in CAN. EtherCAT supports the entire CANopen family, another IEC standard EtherCAT fits within. In addition to CANopen, EtherCAT supports the Sercos drive profile. The drive profiles allow you to configure the EtherCAT network to your specific needs without “reinventing the wheel.” Basic profiles are predefined, which just makes your life as a control engineer so much easier.
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