RoboteQ Dual Channel Digital Motor Controller AX500 - Manual (Page 75)

AX500 Motor Controller User’s Manual 75
Adjust Offset and Max Speed
Important Warning:
If there is a polarity mismatch, the motor will turn in the wrong direction and the
speed will never be reached. The motor will turn continuously at full speed with no
way of stopping it other than cutting the power or hitting the Emergency Stop but-
tons.
Determining the right polarity is best done experimentally using the Roborun utility (see
“Using the Roborun Configuration Utility” on page 131) and following these steps:
1. Disconnect the controller’s Motor Power.
2. Configure the controller in Open Loop Mode using the PC utility. This will cause the
motors to run in Open Loop for now.
3. Launch the Roborun utility and click on the Run tab. Click the “Start” button to
begin communication with the controller. The tachometer values will be displayed
in the appropriate Analog input value boxe(s) which will be labeled Ana 1 and Ana 2.
4. Verify that the motor sliders are in the “0” (Stop) position.
5. If a tachometer is used, verify that the measured speed value read is 0 when the
motors are stopped. If not, trim the “0” offset potentiometer.
6. Apply power to the Motor Power wires. The motor will be stopped.
7. Move the cursor of the desired motor to the right so that the motor starts rotating,
and verify that a positive speed is reported. Move the cursor to the left and verify
that a negative speed is reported.
8. If the tachometer or encoder polarity is the same as the applied command, the wir-
ing is correct.
9. If the tachometer polarity is opposite of the command polarity, then either reverse
the motor’s wiring, or reverse the tachometer wires. If an encoder is used, swap its
CHA and ChB outputs
10. If a tachometer is used, proceed to calibrate the Max Closed Loop speed.
11. Set the controller parameter to the desired Closed Loop Speed mode using the
Roborun utility.
Adjust Offset and Max Speed
For proper operation, the controller must see a 0 analog speed value (2.5V voltage on the
analog input).
To adjust the 0 value when the motors are stopped, use the Roborun utility to view the
analog input value while the tachometer is not turning. Move the 0 offset potentiometer
until a stable 0 is read. This should be right around the potentiometer’s middle position.
The tachometer must also be calibrated so that it reports a +127 or -127 analog speed
value (5V or 0V on the analog input, respectively) when the motors are running at the max-
imum desired speed in either direction. Since most tachometers will generate more than
+/- 2.5V, a 10kOhm potentiometer must be used to scale its output.