Safety Function Architecture
The BMXSDO0802 module internal architecture performs the safety function as follows:
1 The external 24 Vdc power supply is continuously monitored by the safety processor.
2 Each output consists of 2 switches in series between the external +24 Vdc power supply and the ground. The mid-point value (2) is redundantly read and sent to safety processor. The mid-points measuring values are compared by the safety processor. If the values are not the expected ones, the channel is declared not valid.
3 The low-point value (3) is also supervised in order to perform external wiring diagnostic.
4 The supply voltage from the backplane is monitored to determine if there is an over voltage or under voltage condition.
5 The companion chip supplies the safety processor, continuously diagnoses the safety processor, and monitors backplane voltage.