Basler Electric BE1-BPR - Manual (Page 54)

4-2 BE1-BPR Functional Description 9272000990 Rev J
Figure 4-1. Functional Block Diagram
The isolated, switching power supply generates ±12 Vdc, +5 Vdc, and an isolated +5 Vdc. If the +5 Vdc
digital supply falls outside the defined tolerance, then the microprocessor is reset by the power supply
supervisory circuit. This reset takes the relay off-line and lights the Alarm LED. High capacitance on the 5
Vdc supply maintains oscillography and fault record data stored in RAM (enhanced units only) for 24
hours (at 25°C) when operating power is lost or removed.
Power Supply
If the microprocessor fails for any reason, output pulses to the watchdog timer stop. The watchdog timer
will then take the relay off-line, and light the Alarm LED, and close the alarm output.
Watchdog Timer
Opto-isolators in the contact sensing input circuits provide isolation from the external power supply which
provides power to the contact input circuits.
Opto-Isolators