DCP552 Mark II Digital Control Programmer User's Manual

5-31
■ O2 sensor check (model with CP compensation)
● Objective
As the O2 sensor starts to deteriorate, its output impedance increases. This function
checks sensor output impedance and turns on the O2 sensor error event when the
impedance exceeds 130kΩ.
● Setting
•One of the values set for setup data C71 to C74 is set to 11 to assign the O2
sensor check to an external switch.
•One of the values set for event configuration data setting E01-t to E16-t is set to
142 to assign an O
2 sensor error event.
● Operation
•Two methods are used to perform an O2 sensor check. In one method the external
switch which has been assigned the O2 sensor check function goes from OFF to
ON. This is called a constant check.
•The other method the external switch is turned on each 24-hour period. This is
called an automatic check.
•The impedance is checked when PV1 is 800 °C or more and the O2 input is
1000mV or higher.
•The O2 sensor error event goes on when sensor impedance exceeds 130k;Ω
otherwise it remains off.
•The constant check method is shown below.
•The automatic check method is shown below.
Chapter 5. FUNCTIONS