National Instruments Direct Injector Driver System Manual
© 2013 National Instruments. All rights reserved.
Direct Mode and TMP Mode Commands
When operating DI Driver modules and/or the PFI Driver module in
Direct mode
or
Triggered Multi-Pulse (TMP)
mode
, any of the NI 9411 digital input channels (up to 12) can be assigned to command any of the DI Driver and PFI
.
Engine Position Tracking Signals
When operating DI Driver modules and/or the PFI Driver module in
Engine Position Tracking (EPT) mode
, the
NI 9411 digital inputs are not needed to command driver channels directly because they are commanded by angle-
based setpoints by the software EPT function. However, NI 9411 digital inputs are required for receiving crank and
cam or encoder position signals. Any of the NI 9411 digital input channels can be assigned to crank, cam, and
encoder position inputs to the EPT function via the
for more information about crank, cam, and encoder sensor signal types, and their compatibility with
the NI 9411 module. Refer to the NI
9411 Operating Instructions and Specifications
for detailed information about
digital input specifications.
The 15-pin D-Sub COM pin-12 of each NI 9411 module should be connected to the external commanding system
ground, otherwise the correct logic level of the signal will not be sensed by the NI 9411 module. For single-ended
digital commands, the 15-pin D-Sub “a” pins of the NI 9411 digital input channels must be connected to the signal,
while leaving the “b” pins disconnected, or floating. For differential, or complimentary digital commands, the positive
and negative signal pair should connect to the “a” and “b” pins, respectively.
It is good practice to use external 1K pull-down or pull-up resistors on each digital input command line in case the
commands are unintentionally disconnected. For an active-high command, the digital input should be pulled low,
such that the pulldown resistor is connected between the digital input and ground. For an active-low command, the
digital input should be pulled high, such that the pull-up resistor is connected between the digital input and 5V, or the
main power source. If 5V is used, then the 5V output pins (4, 5) of the NI 9411 module may be used for this purpose,
and the Vsup and COM screw terminals must be powered.
Using External ECU Port Fuel Injector or Ignition Driver Outputs
When using another engine control system to command the DI Driver System, it is likely that the port fuel injector or
ignition driver outputs of the engine controller will be used. Typically, port fuel injector or ignition driver outputs are
lowside driver circuits. This means that one side of the port fuel injector solenoid or ignition coil primary is connected
to battery while the other side (lowside) is connected to the engine controller and programmatically switched to
ground during fuel injection pulses or ignition dwell, respectively. In order to utilize these lowside driver outputs to
command the DI Driver System, a pull-up resistor must be connected between a constant voltage source (such as
5V or battery) and the digital input “a” pin of the NI 9411 module (as described above). Then, the port fuel injector
or ignition output pin of the engine controller must be connected to the “a” pin of the digital input channel to be
commanded. The pull-up resistors act as a low-current load to the fuel injector or ignition outputs of the engine
controller.
This physical arrangement provides for an active-low injection command because the engine controller’s lowside
drivers will pull the digital inputs of the NI 9411 module low when injection events are desired. This configuration
requires the
Invert
button of the associated digital input channel be set to
Active Low
via the
.