From time to time I receive an email asking me about how to calibrate the ARS-USB. In this guide we will see how an ARS is calibrated and for this the best way is without doubt to use the ARSConf.

You can directly run the ARSConf from the shortcut.
Select the ARS-USB COM Port and Open it
During few seconds the ARSConf will read the configuration
Total Rotation

In this field you must enter the angle of rotation that the motor will use. In general, this value is usually the one allowed by the motor, for example 360 or 450º. It is also possible to limit the rotation of the motor to a lower value such as, for example, 90 °

Left Limit

In this field you must enter the CCW/Left limit of the motor; normally it uses to be 000º or 180º

  • If your rotor turns from 0-360 or 0-450 (most Yaesu rotors), in this case the CCW Limit will be 000º
  • If your rotor turns from 180-180 (most HamIV/T2X), in this case the CCW Limit will be 180º

Some customers often use the word “North Centered” or “South Centered” to define how the motor rotates. This way of speaking is represented by this parameter, since North Centered means that the motor starts in the South (180º), is centered in the North and ends again in the South (180º).
In our case, it corresponds to Left Limit = 180º.

CW or Right Limit

Move the rotor to the CW or Right Limit. This limit could be 360º or 450º and depends on the rotor model (some Yaesu rotors allows a 450º rotation). So move manually your rotor to the point you wish was used as the CW/Right Limit.  

In this example we use a Yaesu with 450º rotation, so we have moved the rotor to the 450º position (90º Overlap = 360º + 90º)

In case the Actual ADC value is in the range of 950 to 1021, it would not be necessary to adjust the POT1 trimmer (Gain) (see next section) In this case, simply press the CW Button and the ARSConf will use the current value of the ADC (Analogue Digital Converter) as the right limit value.

POT1 - GAIN Adjustment

With the first start-up of the ARS-USB it is possible that when positioning the motor in its Right/CW limit, the return voltage is very high (ADC> = 1022) or low (ADC <800) In these cases it is necessary or convenient to readjust potentiometer POT1 to get the ADC value at this point to be in the range of 950-1021

CCW or Left Limit

Now move the rotor to the other limit or CCW stop. While manually rotating the motor, the Actual ADC value will decrease until it reaches a value very close to 0. When to rotator is at that position, just press the CCW button Automatically the ARSConf will capture the value of the ADC for this position (in this example the ADC = 10)

Save the calibration

Once you have finished the calibration, remember to save it, so press the SAVE button


it is possible that in intermediate positions of the rotation, important variations can be found between what the ARS calculates and what the Rotor Controller actually shows. In these cases, an offset can be applied to correct these variations. Visit the FAQ’s page: