National Instruments Direct Injector Driver System Manual
© 2013 National Instruments. All rights reserved.
4.6 Engine Position Tracking Setup Window
The purpose of the Engine Position Tracking (EPT) Setup window is to configure angular position tracking of the
engine crankshaft for supervising the generation of engine-synchronous injection commands. The
window contains a tabbed pane with four tabs:
: Tab for configuring parameters related to the EPT functions
: Tab for assigning Top Dead Center (TDC) values to each DI Driver and PFI Driver channel.
: Tab for configuring the crank angle capture of rising edges of Cam1 and Cam2 signals.
: Tab for diagnosing problems with engine position tracking and signals.
Configuration of EPT is only applicable if one or more of the DI Driver modules or PFI Driver module is configured for
EPT mode
. EPT supports a variety of crank and cam signal patterns, including encoder patterns, N-M patterns and
N+1 patterns.
Position Signal Types and Connections
The DI Driver System only supports digital crank and cam position signal types wired to the NI 9411 digital input
module(s). Hall-effect sensors are a common example of digital position sensors. They are active sensors requiring
power and ground. There are a wide variety of Hall-effect position sensors and they typically have three wires.
Some drive their outputs digitally low and high from 0 V (signal ground) to the sensor power supply voltage, resulting
in a square-wave pulse as a trigger tooth passes the sensor. The NI 9411 will accept a high digital voltage level
up to 24V. Other types of Hall-effect sensors have an open-collector or open-drain output which requires a pullup
resistor (typically ~5 KOhm) connected between the sensor output and the sensor power supply voltage. The pullup
resistor should be installed as physically close to the NI 9411 module as possible. The sensor data sheet should be
consulted for properly connecting the sensor to power, ground, and the NI 9411 digital input channel.
The NI 9411 supports both single-ended and differential digital signal types. Hall-effect sensors typically have single-
ended outputs and should be wired to the “a” input pin of its associated digital input channel, while leaving the “b” pin
disconnected, or floating. This configuration causes a default 1.5V threshold for detecting a low (FALSE or 0) or high
(TRUE or 1) digital input. If the sensor requires a different switching threshold, then a voltage other than 1.5 V can
be wired to the “b” pin. This can be accomplished by a simple resistor voltage divider close to the module.
Sometimes, optical encoders have a differential, or complementary pair of outputs for each signal. In this case, the
differential pair should be connected to the “a” and “b” pins of the NI 9411 input channel.
In all cases, the sensor ground should be connected to the NI 9411 COM pin as a voltage reference, otherwise the
module will not be able to read the proper digital signal level. Refer to the
operating manual for the NI 9411
module
for further details.
Variable Reluctance (VR) position sensors are not supported by the DI Driver System. VR position sensors are
passive sensors and are sometimes referred to as inductive or magnetic (“mag”) pickup sensors. They typically have
only two wires. These sensors output a positive/negative sinusoidal waveform with an amplitude proportional to the
speed of the trigger wheel. The NI 9411 digital input module does not support such waveforms.
Supported Pattern Types
The EPT function supports three crank and cam pattern types described in Table 4.6.a below.