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I am new to the field of automation, hence the 'beginner' question:

The goal is to control two servo motors via an iPad app.
I thought of using either a Panasonic or Beckhoff driver, the Panasonic being a bit cheaper but the Beckhoff probably has more features and seems overall better documented.

Since there is no plug-n-play option (at least none I heard of which lets you use your fully custom iOS app), I thought of getting an ethercat driver and connect a Rasperry Pi to it which acts as a link:

[MOTOR]---[DRIVER]---[PI]---wifi---[iPAD]

Anyone ever did something like this and could give me a few hints?

Ajay2707
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user3603948
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  • This is not compleat answer, but only few ponters (I hope it will be helpfull anyway): http://cylonjs.com/documentation/drivers/continuous-servo/ or https://github.com/fibasile/Firmata-ObjC, http://raspberrypi-aa.github.io/session3/firmata.html, http://firmata.org/wiki/Main_Page – Maciek Sawicki Jan 01 '16 at 23:00
  • thanks for your input, I will probably do it with an embedded webserver. I would still need help on how to 'talk' to the servo drive from the Pi. If anyone could point me in the right direction that would be great (working my way through the servo drive manuals right now) – user3603948 Jan 04 '16 at 14:44

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EtherCAT requires a master stack which can be gotten from a variety of places. I believe the IgH EtherLab stack has been successfully compiled and used on the rPI, with some caveats. The rPI ethernet port is apparently connected via USB. In theory this will work, since the EtherLab stack can use a generic driver for accessing the ethernet Rx/Tx paths.

Here's the mailing list post from 2013 with a few folks discussing this.

Speed8ump
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It depends on what kind of servo motor you're planning to control. Beckhoff deals with motor with high torque and industrial grade. If the normal hobbyist low torque servo motor works for you, you don't need a driver for it. Just connect the motor to the Raspberry Pi. I'm referring to this kind of servo motor: https://www.adafruit.com/product/155

Beckhoff servo motor requires Beckhoff motor driver, which is quite big and expensive. The motor driver communicates through EtherCAT. You need to make the Raspberry Pi to be an EtherCAT master. You can install Codesys in your Raspberry Pi, but I'm not really sure how the whole thing works with Codesys.

The hard way would be to get Simple Open EtherCAT Master (SOEM) running in your Raspberry Pi, but that is also not very straight-forward.

Other motor driver uses other types of communication (eg pulse line, Modbus), you need to check with the specs.

Stucky
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