900719_FOCE : Notes on EZServo This page last changed on Jul 11, 2008 by bobh. You must have the firmware updated to the latest release, or some of the commands we use won't work correctly. As of this writing, the latest release is V6.999. You can check the firmware release with the command /1& (for controller 1) The initialization string that we use is /1s0N1u500m100V0P0L1000R This can be desconstructed as follows: s0 - Store this as command 0, which will cause it to be executed if the controller resets N1 - Position mode, Encoder with No Index. Still accepts velocity commands, but gives us more resolution on the velocity. u500 - Overload time, 500 ms m100 - Use 100% of max overload current V0 - Initialize to zero velocity P0 - Move motor in positive direction. A value of 0 will cause an endless forward move at a speed specified by V. If we want to move in the negative direction, we'll override this command with D0. L1000 - Acceleration in encoder ticks/sec^2 R - Run the command immediately #### Other Useful Commands /1Vxxx - Set velocity. /1V2204 will set a velocity of 1000 RPM, so the multiplier is 2.204 /1T - Cancel command /1r1 - Reset controller /1Q - Status /1& - Get firmware revision /1?8 - Get encoder position ##### Status Typical results you may see from /1Q, and interpretations i = 0x69 , overloaded ` (backtick) = 0x60 - Ready, not running @ = 0x40 - Running O = 0x4f - Command overflow. This indicates a command was already running. But it's a normal response. My code takes the response code, ANDs it with 0x6f, and expects the result to be either 0x40 or 0x4f as a successful response to a velocity command; anything else is treated as an error. ##### Velocity Calculations Observed max speed in air is 10300 RPM before overloading. It will be much smaller in water. Motor 10300 RPM /1V22700 172 Hz observed on scope at Hall encoder 11.4 RPS shaft speed (15:1 gear down) Calculated results to generate 10 cm/sec Motor 1000 RPM /1V2204 Hall sensor: 16.7 Hz Shaft speed 1.11 RPS Given these parameters, it appears that in Position mode (N1) we can control the speed to .454 RPM motor speed.

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