Undervoltage protection
The undervoltage protection prevents connected devices from being operated with a supply voltage that is too low. A malfunction of the devices due to undervoltage is thus impossible.
The undervoltage protection has two threshold values, see Technical data:
- Uwarn: If a supply voltage US or UP falls below the upper threshold value Uwarn, the bit "Warning Us" or "Warning Up" in the process data object "DPO Inputs Device" is set.
- Uerr: If a supply voltage falls below the lower threshold value Uerr, all outputs are switched off and the bit "Error Us" or "Error Up" in the process data object "DPO Inputs Device" is set.
The threshold values of the undervoltage protection cannot be parameterized.
Disabling for Up
You can disable the undervoltage protection for the peripheral voltage UP by setting the CoE parameter F80E:05 "Disable Up Undervoltage Error" to TRUE. That is useful in applications in which UP is not needed. In such applications UP would otherwise only have to be connected so as not to trigger the undervoltage protection.
Resetting an error state
If the output voltages have been switched off by the undervoltage protection, they can be re-activated in two ways:
- a positive edge on the output variable
„DPO Inputs Device“ > „Global Reset“. - A voltage reset of US
Requirement: Both supply voltages are higher at this point in time than the upper threshold value Uwarn.