Timing and Synchronization of the Event Data Recorded by the Electronic Control Modules of Commercial Motor Vehicles - DDEC V 2013-01-1267

It is well recognized that Heavy Vehicle Event Data Recorder (HVEDR) technology has been incorporated in the Electronic Control Modules (ECMs) on many on-highway commercial motor vehicles. The dynamic time-series data recorded by these HVEDRs typically include vehicle speed, engine speed, brake and clutch pedal status, and accelerator pedal position. With specific respect to Detroit Diesel ECMs, data are recorded surrounding certain events at a rate of 1.0 Hz. In this research, controlled testing was conducted to determine the time differences between the values being generated by the sourcing sensors and the interpreted data being broadcast on the vehicle's SAE J1939 controller area network (CAN). To accomplish this, raw sensor data as provided to the ECM was monitored, as were the subsequent J1939 CAN transmissions from the ECM. Several of the monitored parameters were then simultaneously changed through the use of a switch to determine timing between state change, receipt by the ECM, and J1939 CAN broadcast. Testing with the switch that simultaneously changed the states of four of the five monitored parameters established the time lags that exist between when the sourcing signal was generated and when the value for this signal was broadcast on the vehicle's J1939 CAN and reported by the HVEDR function of the DDEC V ECM. Testing with the switch also established that the data reported by the HVEDR function of the DDEC V ECM are asynchronous. Finally, the timing and synchronicity of the Electronic Engine Controller #2 (EEC2) and Cruise Control/Vehicle Speed (CCVS) Application Layer Parameter Group Numbers that are broadcast by the DDEC V ECM over the vehicle's J1939 CAN was determined. In addition, the Electronic Engine Controller #1 (EEC1) Application Layer Parameter Group Number was determined to broadcast asynchronously over the vehicle's J1939 CAN.