# 4.3.9. Critical parameters¶

Minimum and maximum values of currents, voltages and temperatures are used for safe controller operation. Any value out of acceptable range leads to the motion stop, windings power-down and Alarm state for the controller. Exiting the Alarm state is possble only after the critical parameter returns to normal and the STOP command is sent to the controller. Critical settings are used for all motor types.

The following parameters are available:

• Low voltage off defines the minimum voltage value of the controller power supply (measured in tens of mVs). The Low voltage protection flag is used to turn this option on, otherwise the minimum unpowering threshold doesn’t work. The 6000mV to 8000mV range is sensible for operating power range of 12V to 48V. This type of protection helps to determine the power-cut moment due to activation of any sort of power supply unit protection. This may occur if the operating power consumption of the stabilized power supply unit is exceeded.
• Max current (power) defines the maximum current of the controller power supply (measured in mAs). The sensible value is twice the maximum operating consumed current registered during the tests. Use the XiLab charts for registration of the consumed current.
• Max voltage (power) defines the maximum voltage value of the controller power supply (measured in tens of mVs). The sensible value is $$20\%$$ higher than power supply unit voltage.
• Max current (usb) defines the maximum current of the controller power supply via the USB cable (measured in mAs). The controller demands the current received via USB interface for its own needs (150mA) and for supplying the power to the devices connected to the motor’s connector (200mA). This limitation is sensible within the range of 250mA to 450mA, depending on external devices powered by the controller. The USB interface is not designed for the current of over 500mA, although it is often able to stand the 1000mA to 1500mA current.
• Max voltage (usb) defines the maximum voltage value of the controller power supply via the USB cable (measured in tens of mVs). The controller may get damaged if the USB power supply voltage exceeds 5.5V value. Thus, 5.2V is the sensible limitation.
• Min voltage (usb) defines the minimum voltage value of the controller power supply via the USB cable (measured in tens of mVs). The controller doesn’t work if the power voltage supplied via the USB interface is less than 3.6V. The voltage is measured at the controller input. Low-quality USB cables may have different voltages on its ends in the presence of current. At least 4.0V voltage is required if the consumed current is high. The sensible value of the minimum voltage limit is 3.8V.
• Temperature defines the maximum temperature of the microprocessor (measured in tenths of degrees Celsius). The microprocessor can operate at the working temperature of up to 75ºC and doesn’t overheat by itself. Rise of its temperature indirectly indicates the overheating of the power part of the board. The overheating threshold range from 40ºC to 75ºC is sensible.

Flags:

• ALARM_ON_DRIVER_OVERHEATING means entering the Alarm mode if the driver’s critical temperature (over 125ºC) is exceeded. The power driver indicates if its temperature is approaching the critical value. If the driver is still working then the further heating will automatically shut it down. It is recommended to set this flag and not to rely on automatic forced shutdown.
• H_BRIDGE_ALERT means turning the Alarm mode on if any fault of the power driver due to board overheating or damage is detected. This flag should be set on.
• ALARM_ON_BORDERS_SWAP_MISSET means turning the Alarm mode on if the triggering of the wrong limit switch, not corresponding to direction, is detected (see the Limit switches chapter). This flag is intended for clear indication of the response of the limit switch swap detection subsystem. The flag is recommended to be set on.
• ALARM_FLAGS_STICKING flag activates the sticking of the error indicators in the status structure of the controller, otherwise indicators are active only during the accident that caused the error. If there was a short-time error and its cause was independently removed, then sometimes the reason of Alarm remains uncertain. In that case the sticking is useful and the accident cause can get diagnosed in XiLab main window.
• USB_BREAK_RECONNECT - This flag configures the operation of an USB break reconnect block. When set, this unit starts to operate and monitor the loss of communication over the USB bus (for example, in case of a static discharge).

Configuration of parameters is described in Critical board ratings menu of XiLab software. The maximum available value configuration commands are described in Programming guide.