National Instruments Direct Injector Driver System Manual
© 2013 National Instruments. All rights reserved.
3.5 Optimizing The DI Driver System
When connecting multiple injectors to a DI Driver System, there are a few optimizations to consider.
Simultaneous or Overlapping Injection Events
A DI Driver module uses multiplexed circuitry to provide up to three driver channels within the module for solenoid
direct injectors and two channels per module for piezoelectric direct injectors. Therefore, only one channel within the
module may be operated at a time. If injection events within a DI Driver System must be operated simultaneously,
the simultaneous events must be connected to channels on separate DI Driver modules.
Channel Sequencing
When operating multiple sequential direct injectors, the operating sequence of channels should be planned so that
the time between injections events within a single module is maximized. For example, as shown in Table 3.5.a, an
8-cylinder 4-stroke engine will have injection events separated by 90 degrees. If a 12-Channel DI Driver system is
used, sequential injectors should be staged from one DI Driver module to the next. By doing this, channels within a
single module will have a spacing of 360 degrees, providing maximized time for boost power supply charging and
multiple injection events per cylinder.
8-Cylinder, 4 Stroke Engine With 12-Ch DI Driver System
Injection Event
CAD
DI Driver Module
Channel
1
0
1
1
2
90
2
1
3
180
3
1
4
270
4
1
5
360
1
2
6
450
2
2
7
540
3
2
8
630
4
2
Table 3.5.a, Optimization of 8-Cylinder, 4 Stroke Engine With A 12-Ch DI Driver System
Injection Command Duration Limitation
The maximum allowed injection pulse command is internally limited to 5 milliseconds. If an external or internal
command is generated which exceeds 5 milliseconds, the actual injection pulse will be halted at 5 milliseconds.
If multiple external direct commands are active simultaneously on a single DI Driver module, then all three driver
channels of the module will be made inactive until only one channel is commanded.