The PID/Data Monitor and Record option allows the scan tool operator to read the state of several Parameter IDs (PIDs) to aid in diagnosing the system. PIDs are real time measurements of parameters such as voltages, resistances, etc., calculated by the air bag Electronic Crash Sensor (ECS) module and sent to the scan tool for display. Many of the PIDs supported by the ECS are calculated periodically and are, therefore, not true real time readings.