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How To Choose A Motion Bus
Looking for feedback - Article here: Motion Bus
Compares SynqNet, EtherCAT, SERCOS III, PROFINet, Powerlink and others.
Excerpt
In order for motion busses to offer high cyclic update rates, the packet usage or packet structure have been adapted from classic Ethernet usage to increase the network’s data efficiency. The rates that are actually achievable depend on network loading and controller processing capability; communicating with 100 single axis nodes at 1 kHz or servicing 10 single axis nodes at 10 kHz are indicative of busses designed specifically to handle motion. Note however that although the cyclic rate is the industry figure of merit, control latency is more important for achieving tight control. Published data are scarce so be sure to ask your supplier – especially if you plan to close loops via the network.
Hybrid networks aspire to combine the flexibility of the general-purpose network with predictable timing for motion control. They support a mixture of scheduled and unscheduled traffic along with distributed clocks. They are capable of sending command values to some number of axes at low cyclic rate, such as =1 kHz. Loop closure through the network is not generally feasible with hybrid networks but nevertheless they have an appeal – particularly where the network in question is already in use at plant level.
Compares SynqNet, EtherCAT, SERCOS III, PROFINet, Powerlink and others.
Excerpt
In order for motion busses to offer high cyclic update rates, the packet usage or packet structure have been adapted from classic Ethernet usage to increase the network’s data efficiency. The rates that are actually achievable depend on network loading and controller processing capability; communicating with 100 single axis nodes at 1 kHz or servicing 10 single axis nodes at 10 kHz are indicative of busses designed specifically to handle motion. Note however that although the cyclic rate is the industry figure of merit, control latency is more important for achieving tight control. Published data are scarce so be sure to ask your supplier – especially if you plan to close loops via the network.
Hybrid networks aspire to combine the flexibility of the general-purpose network with predictable timing for motion control. They support a mixture of scheduled and unscheduled traffic along with distributed clocks. They are capable of sending command values to some number of axes at low cyclic rate, such as =1 kHz. Loop closure through the network is not generally feasible with hybrid networks but nevertheless they have an appeal – particularly where the network in question is already in use at plant level.
Replies to This Discussion
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Permalink Reply by Andrew Feliks on -
I use in my work easy motion bus -DMX 512 .Its implementation RS 485 for Light, and motion on stage.
I think , so if can buy a spec IC wit DMX reviver and transmitter e.g. 48 channel o- 10 v in one chip, this bus will popularizes in big market. Its enough for many easy using in home ,easy commercial etc. All light in big concert are using this bus . Its look very complicated.
Andrew
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Permalink Reply by David Fischhaber on -
Am requesting membership in this group.
Thank you.
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Permalink Reply by David Fischhaber on
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Overall, a nice article - if taken as a cursory overview.
Have used most of the listed networks. All work just fine for most applications.
Our company has chosen to focus on EtherCAT. It's the fastest of the networks (communicates with 100 drives - single or dual motor drives - in 100 microseconds). It's the least expensive. It handles I/O at the rate of: 256 digital I/O in 11 microseconds or 1000 digital I/O in 30 microseconds or 200 of 16 bit analog in 50 microseconds. When it comes to interfacing with other networks you can run Profibus, Devicenet, Canbus, and even regular Ethernet on the same network. Lastly, it also has network-based safety (handles E-Stop, Safety Relay functions, etc.) and even has a redundancy option (i.e., if there is a cable break, the system will still keep running).
There are other very nice features but I think you get the point. The other networks are fine but why use them when you can use one that does everything and costs less to use. We use it for all applications.
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