RoboteQ AX2850 user manual Speed Sensor and Motor Polarity

Speed Sensor and Motor Polarity

Connecting the tachometer to the controller is as simple as shown in the diagram below.

1kOhm

Zero Adjust 100 Ohm pot

1kOhm

	+5V 14
Max Speed Adjust	Ana 1: 11
10kOhm pot
	Ana 2: 10
	Ana 3: 12
Tach	Ana 4: 8

Ground 5

Internal Resistors and Converter

47kOhm

A/D 10kOhm

47kOhm

FIGURE 63. Tachometer wiring diagram

Speed Sensor and Motor Polarity

The tachometer or encoder polarity (i.e. which rotation direction produces a positive of negative speed information) is related to the motor’s rotation speed and the direction the motor turns when power is applied to it.

In the Closed Loop Speed mode, the controller compares the actual speed, as measured by the tachometer, to the desired speed. If the motor is not at the desired speed and direc- tion, the controller will apply power to the motor so that it turns faster or slower, until reached.

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 177) 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. If encoders are used, look for the reported speed value in the Enc boxes.

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.

AX2550 Motor Controller User’s Manual 99