RMS Technologies R208 DRIVER - Manual (Page 9)

RMS Technologies Page 9 Version 1.22
R208 Microstepping Driver Manual 8/31/2007
Adjusting the Output Current
Before connecting a step motor to this driver, use the following procedure to check
the output current of the R208 unit. The default output current is set at 1.0 Amp.
WARNING! – To avoid damaging your step motor with the default setting,
the output current should be adjusted before connecting the step motor.
1. Ensure that the step motor is not connected to the R208 unit. Do not supply
pulse input to the R208 unit while adjusting the Output Current. This will
affect the voltage level reading on the voltmeter.
2. Place one probe of the voltmeter through the slot of the cover and attach it to
the lead of the potentiometer. The other probe of the voltmeter shall be
attached to Pin #7 of the mating connector assembly (Part # 90-019).
3. Apply the appropriate power supply to the R208 unit.
4. In order to decrease the current output, adjust the potentiometer in the
clockwise direction using a flathead screwdriver. Please use the following
formula to obtain the desired current output:
• Current, I = 2.22 x V
ref
* + 0.14 when cutback current function is enabled
• Current, I = 0.72 x V
ref
* + 0.14 when cutback current function is disabled
• V
ref
= (I – 0.14)/2.22, where I = Motor’s Rated Current (RMS Value)
To achieve more power when running a motor rated less than 1.4 Amp, use Peak
Current, which will multiply the Motor’s Rated current by 1.4 Amps. Please use
this formula:
V
ref
= (I – 0.14)/1.554 (I is still the Motor’s Rated Current)
Currently, the default setting is at V
ref
= 0.55 VDC = (1.0 Amp – 0.14)/1.554
*Reference Voltage refers to the voltage level across the potentiometer.
Figure 3: Adjusting the output current