# 2. Safety instructions¶

## Power supply and grounding requirements. Connection to controller¶

General requirements for a controller board, systems in box (single and double axes) and multi-axis system are listed below.

IMPORTANT. Either the power supply unit should be plugged to grounded 220V AC socket (a three-wire connection scheme). Make sure that the minus electrode of your power supply unit is grounded. If the power supply unit with minus electrode disconnected from the grounding circuit is used, ground the controller board via special grounding terminal (look at the picture below). Non-compliance with these rules may lead to the decrease in controller stability and noise resistance.

Top view of the controller board. A grounding terminal marked with the red square

Typical connection diagram for a controller (board, systems in box):

Controller grounded via minus electrode of power cable connection diagram

Controller connection diagram with grounding via special terminal

Warning. Power supply unit should be able to supply sufficient current to rotate the motor. As an absolute minimum it should be able to supply $I_{power.min}=\frac{2*I_{motor}*U_{motor}}{U_{power}}$ where $I_{power.min}$ is the minimum working current of power supply unit, $I_{motor}$ is the operating current in the winding, $U_{power}$ is power supply unit stabilized voltage, and $U_{motor}$ is rated operating voltage of the motor. It is recommended to use a power supply unit with operating current equal to $I_{power} \geq 2*I_{power.min}$. The $U_{power}$ voltage should be greater than $U_{motor}$. The higher the voltage, the faster rotation speed could be reached.

One can use power consumption of power supply unit to calculate minimum requirements instead. An absolute minimum of power is $W_{power.min}=I_{power.min}*U_{power}=2*I_{motor}*U_{motor}$. For example, for motor with operating winding current of 1A and operating voltage of 5V (with 5W rated power consumption), the operating voltage of power supply unit may be chosen at 20V with the output power of at least 10W (the maximum operating current of power supply unit is at least 0.5A).

## Controller board¶

IMPORTANT. It is strictly forbidden to touch the controller board without any antistatic equipment. We recommend you to use antistatic wrist strap.

IMPORTANT. It is strictly forbidden to connect positive wire of power supply to the controller board when ground wire is not connected. It is strictly forbidden to connect or disconnect power cable when the power supply is on, the controller is connected to the PC and the power supply and the PC are grounded. This may damage the PC! This is a common requirement for any electronic device with separate power source, which is connected to the PC via USB.

Warning. Before connecting the controller board to the motor or to the PC via USB interface, it is recommended to connect controller to power supply with proper grounding or to use separate grounding for controller with the specially marked ground terminal (look above).

## One and two axes system in box¶

IMPORTANT. You should not exceed maximum allowed voltage of 36V. If voltage goes over allowed value at more than 2 volts, it can immediately and irreversibly damage the controller.

## Multi-axis system¶

The main feature of multi-axis system is 220V power connection, whereas power supply requirements listed above are not related to this system.

General multi-axis system connection diagram.

IMPORTANT. Multi-axis system should be plugged to grounded 220V AC socket (three - wire connection). Non-compliance with this rule may lead to the decrease in system stability and noise resistance.

IMPORTANT. It is prohibited to touch inside the box while module is disconnected. There is 220V!

Note: Multi-axis system supports modules hot-plug and sudden disconnect of power supply 220V.