PVC_ValveDiagnostic (FB)

Description

This function block provides short circuit / broken circuit and feedback diagnostic for one valve. Valve control circuit resistance is used for diagnosing short circuit and broken circuit errors.

A shortcut in circuit with high-side current measurement.

A shortcut in circuit with feedback current measurement.

A short circuit error is generated when the measured resistance is continuously equal or less than half of the given value for given error delay time. PWM control must be over given minimum G_PVC_MIN_PWM at the same time.

Short circuit is also diagnosed from oscillating feedback and high feedback current. These two methods have no error delay applied. Oscillation status is active when the feedback rises and falls more than 50% for 10 times. High feedback current status is active when the feedback current has not changed after 5 sequential decrements of 5% in the PWM request.

A broken circuit error is generated when the measured resistance is continuously 5 times greater than the given value for given error delay time.  PWM control must be over given minimum G_PVC_MIN_PWM at the same time.

A feedback error is generated if the measured feedback current is over the given maximum leak current when the control request is not active. The maximum allowed leakage current is defined in global G_PVC_MAX_ALLOWED_LEAK_CURRENT.

Limitations

Inputs

Outputs

Example code

See also

• PVC_CurrentValvePairController (FB)

• PVC_SingleCurrentValveController (FB)

• PVC_CurrentController (FB)