How to check if the Hall sensors are linear (analog) or digital [II]

Many of the brushless motors available on the market today are equipped with Hall effect sensors. Usually, these Hall effect sensors are digital. However, there are certain types of motors equipped with linear (analog) Hall sensors.

While Technosoft drives currently use the digital Hall effect sensors only as commutation feedback, the linear (analog) Hall effect sensors are used as a position and / or speed feedback device.

Remark: A HALL effect sensor is a transducer that varies its output in response to a magnetic field.

Usually the type of the Hall sensors is mentioned in the motor leaflet or data sheet. In case the motor manufacturer doesn’t provide this information, the simplest way to check if the Hall sensors are digital or linear is to use a voltmeter.

While the Hall sensors are supplied (usually with 5 Vdc), the voltmeter has to be connected between one of the Hall sensors outputs and ground. Then the motor shaft needs to be slowly rotated manually while checking the indication of the voltmeter. If the voltage variation is linear then the Hall sensors are linear (analog). If the voltage will jump form 0 V to 5 V and back then the Hall sensors are digital.

Remark: An oscilloscope can also be used Instead of the voltmeter. In this case the shape of the signals will be more clear.

While most Technosoft drives support both linear (analog) and digital Hall sensors, care must be taken where the Hall sensors outputs are connected to the drives. Each type of Hall sensors has its own set of input pins. Digital Hall sensors must be connected to the HALL1, HALL2 and HALL3 pins, while linear (analog) Hall sensors must be connected to the LH1, LH2, LH3 pins.

The type of the Hall sensors can also be checked using the drive. For that, the sensors need to be connected to the linear Hall sensors inputs (LH1, LH2, LH3).
In EasyMotion Studio or Easy SetUp, a linear hall sensors template must be opened.
In the Motor Setup dialogue, the « Hall Signals Connection Test » must be run. If the variation of the signals displayed during the test is linear, then the Hall sensors are linear (analog). Otherwise, if the signals appear to have a square wave variation like in the picture below, the Hall sensors are digital.