EtherCAT and Servo Drives. - Page 1
Forum section: electronics / projects

author: CM800
author_rank: Frequent Contributor
timestamp: January 07, 2015, 11:37:20 pm
content: I was just wondering if anyone on here has some experience with designing Servo Drives and implementing EtherCAT into products?I am looking at doing both in my new job position, does anyone have any pro-tips or useful resources?I'm also trying to decide on what kind of micro-controller / FPGA to use (I don't have too much experience with these things however I am a quick learner)So far I've looked at PSoC and STM32F, considering looking at Atmel AVR micro-controllers. I'm mostly trying to get a bit of a footing in all this as I was dumped in the deep end at the job.Thanks,Thomas W

author: max_torque
author_rank: Super Contributor
timestamp: January 07, 2015, 11:57:12 pm
content: Look very carefully at the temperature ratings for your chosen components and how they meet the specs of the industrial device you are designing!

author: dgtl
author_rank: Regular Contributor
timestamp: January 08, 2015, 12:05:32 am
content: Trinamic (trinamic.com) had some EtherCAT motor control demonistrations; i believe i saw those at some expo (Embedded World?). They have some nice chips to offload some of the control tasks from your uC.AVRs and ARMs are two different worlds. There are a lot of ARM Cortex-M vendors. The actual selection can be made after you know your performance requirements and the interfaces you need. PSOC's have a nice configurable HW that allows offloading some interface tasks to HW and you might be able to work with a less-powerful cpu core. Definitely you should check also NXP LPC, STM32, Atmel SAM's, Silabs/Energy Micro geckos, Spansion/Fujitsu FM, Freescale etc. All have their strenghts and weaknesses. For beginners, I would suggest NXP due to the LpcXpresso tools, that make getting started much easier. Later on, you can just choose another cortex-m uC and use non-vendor-branded toolchains (ie gcc) for whatever cortex-m based uc. The peripherals are different, the cpu core is the same. If you are familiar how the thing is programmed with gcc, the same can be done with whatever other cortex-m. Just some vendors have easier getting started tools than others.

author: sca
author_rank: Regular Contributor
timestamp: January 08, 2015, 12:53:27 am
content: Not sure how much things have changed, or if you're already ahead of me in your research, but I looked into this for a customer some time ago, and went on some of Beckhoff's seminars on Ethercat.Certainly as of a perhaps 3 years ago, you'd really need to be looking at either one of the purpose built Ethercat chips, or perhaps a lot of work with an FPGA. As the Beckhoff guru described it, Ethercat achieves its high performance by reading and manipulating packets 'on the fly' as they're clocked through a shift reg at bus speeds. There's no time for the more usual ethernet style buffer - read - write - re-package / calc CRCs - transmit cycle.I seem to recall there were a couple of vendors of the ASICS, and it wasn't too difficult to get information or join the industry group, though I may be out of date here.I did see Freescale suggesting they had a Cortex with Ethercat at a show perhaps 18 months ago, but on talking to the only guy on the very small stand, it seemed to be largely vapourware - what they really had was Profibus. This of course may have improved in the meantime.sca

author: chickenHeadKnob
author_rank: Super Contributor
timestamp: January 08, 2015, 08:22:12 am
content: Quote from: sca on January 08, 2015, 12:53:27 amTI sells a demo board based on the AM3358 tidep0001http://www.ti.com/tool/tidep0001. This can do ethercat slave I believe. You have correctly identified the Achilles heel in all loop/ring topology industrial networks, namely the slaves need to do some really low latency operation ricky-tic at the end of one packet before the next one overruns. The critical processing needs hardware assist, in the sitara part mentioned above it is handled by one or both of the PRU-ISS. That transfer of difficulty means ethercat slaves are the expensive ones not the master, which can be any old ethernet port, and that is an unfavorable cost inversion. You want the slaves to be cheap and simple because there are always more leaf nodes as captain obvious would say.The ethercat companies all claim open standard and give master node code away, but they then retain a proprietary grip on slave software or fpga IP. I love rings for deterministic messaging and have used SDLC loop mode and bitbus in the past but they have never been cheap.

author: CM800
author_rank: Frequent Contributor
timestamp: January 08, 2015, 12:38:30 pm
content: Thanks everyone for the information. I have been contacting EtherCAT and getting my company membership (waiting for them to send the paperwork currently)My current concern is in fact how to implement the EtherCAT slave...Has anyone actually -done- it on here?