11-05-2008, 09:56 AM
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| | | Join Date: Jan 2006 Location: USA
Posts: 58
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The parallel port outputs TTL signals: digital on/off signals at 0V and either 3.3V or 5V. You'll definately need interface electronics to convert that to +- 10V. Servo amps that take +-10V expect to see voltages in that whole range, with the input voltage proportional to motor speed or torque. It's fundamentally analog rather than digital.
Servos also provide feedback to EMC2, usually in the form of quadrature encoder signals. These signals need to be sampled at very high speed; depending on the encoder hardware on the servo it might need anywhere from several hundred KHz up to a several MHz. This is much too fast for EMC2 to read over the parallel port, you need dedicated encoder counting hardware for this to work.
EMC2 works with a lot of interface electronics, including boards that convert digital signals to +-10V and boards that count quadrature encoder signals. There may be open designs for boards like this, but I dont know of any.
Here is a list of hardware known to work with EMC2: EMC2 Supported Hardware
Here is the front page of the EMC2 wiki, it's got a ton of good info on configuring EMC2: EMC2 Wiki.  |
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