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Throttle Simulator for Cummins EDC (Electronic Diesel Control).



Running a large Diesel Engine (EDC Controlled) as a Stationary Plant being a Generator set or any other industrial Test-rig system there is a limitation associated with it, that is when the engine is in a Truck or Vehicle application there is a driver that request Torque and Power required by the use of the Driver throttle pedal,in an stationary application there is no driver to operate this Driver Pedal(TPS) and in such applications there is the need for a intelligent system that automatically detects and predicts the next operation(close loop control) point normally this is done by the Plant Industrial Controller such as National Instrument PXI system ,a Beckhoff system or a MIAC (MATRIX AUTOMATION CONTROLLER).


National Instruments PXI


MIAC Controller



The TPS Simulator Operation


The TPS Simulator interface the Industrial controller to the EDC Engine Controller by replicating the two needed TPS signals(TP1 and TP2) that the EDC control units is expecting.Due to the critical safety issue related to the Driver Pedal signal if any one is missing or not within the tolerance expected by the Engine EDC controller the EDC controller goes into what is know as limp home mode and the Engine will possibly only Rev up to around 1200 to 2000 Rpm with huge torque reduction very poor drive ability and in stationary application this means the plant is not working at all as intended.

The Automation Controller send a standard 0 - 10V analog signal that represent 0 -100% throttle positions to the TPS Simulator(Translator) which then reads this signal and generate the two signals (TP1/TP2) to fit exactly on the curve that is programmed in the EDC Controller.The EDC Controller is happy and it accepts these signal and operate the Engine

as requested. All Safety related parameters in the EDC is still active and will be triggered if any thing goes wrong



Block Diagram of the Integration of the Various System Components




Below the Original Signals Measured and Plotted.


The Generated Signals

The Range of the Signals correspond with the original signals between 2-9V input signal below and above are used by the industrial controller to detect some special request from the Plant and as you notice at 2V input we have the 1 and 0.5 V respectively for the EDC Controller



CAD Layout of the TPS Simulator PCB




TPS Simulator Diagnostic Interface

The TPS Simulator uses a standard UART Serial interface which allow a PC GUI application to communicate with it for calibration and diagnostic purposes.




Firmware Realization


The Firmware was realized with Flowcode, the following Flowcode Components were used

  • DAC Component

  • ADC Component

  • UART Component

  • IO Components

  • All Coding were done with Flowcode blocks


Example Flowcode Code





Conclusion

Using Flowcode with all its included Components makes such complex applications easy and can be realized in very short times.

The Code can easily be transferred between different Vendors such as ARM, PIC etc

The code is easily maintained as it is easy to read, it is in Flowchart form.


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