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requires the Invert button of the associated digital input channel be set to Active Low via the Digital Input Setup
window .
Using ECU PFI or ignition driver outputs to command DI Driver System injection events requires that the DI Driver
module or PFI Driver module be configured for Direct mode or TMP mode via the DI Driver Setup window or the
PFI and LS Driver Setup window .
Since most engine controllers have diagnostic features to detect fault conditions with the fuel injector or ignition
loads, and pull-up resistors are not inductive loads, the engine controller may report open-circuit faults. Such faults
should be ignored. If the engine controller refuses to operate the channels due to such faults, then another command
method must be arranged. Figure 3.3.3.4.c illustrates this configuration.
Figure 3.3.3.4.c, Connecting an Engine Controller Port Fuel Injector Output to the DI Driver System
Using External ECU Direct Injector Driver Outputs
When using another direct-injected engine control unit (ECU) to command the DI Driver System, it is sometimes
possible to use the ECU direct injector driver outputs. However, it is likely that an ECU direct injector driver output
will not tolerate resistive loads and internal faults will be generated which will shut down the ECU channel. Typically,
ECU direct injector driver outputs will have a positive and negative terminal for each injector. The negative terminal
is a lowside switch to ground and can be connected similarly to Figure 3.3.3.4.c. If the engine controller refuses to
operate the channels due to diagnostic faults, then another command method must be arranged.
Using Transistor-Transistor Logic (TTL) Commands
If general purpose Transistor-Transistor Logic (TTL) commands are used from an external controller, then the TTL
commands may be directly connected to the “a” pins of the NI 9411 module. The commanding device ground must
be connected to the NI 9411 module COM pin. The NI 9411 “b” pins may be left disconnected.