Innovate Motorsports DL-32 - Manual (Page 20)

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can be up to 29.4 PSI above atmospheric pressure. Vacuum is typically measured here as
negative PSI. But you can set up any metric you want with LogWorks 2.
9. Measuring Frequencies, custom RPM, or speed
The DL-32 has the capability to measure frequencies on channels 3, 4, and 5. It converts a
frequency signal (pulses per second) into a voltage (0..5V) to be logged in the LM-1 or a number
between 0 and 1023 to be logged directly by LogWorks. This is useful for measuring custom
RPM ranges, signals from speed sensors or the frequency of MAF sensors with frequency output
(as opposed to voltage output MAF sensors).
The range of frequencies that the DL-32 can measure can be programmed by with LM
Programmer. The DL-32 can be set to any frequency range between 0 and 30 Hz for the full
0..5V range to 0..15 kHz for the full 0..5V output (logging) range.
Also, LM Programmer has convenient conversions built in, so you don’t have to calculate the
resulting frequency ranges for speed sensing or RPM sensing yourself.
A frequency input signal must have an amplitude (voltage range of pulse) between 0.5V at the
low pulse point to minimum of 3V and maximum of 40 V at the high pulse range.
NOTE:
The custom RPM feature will work only for even fire tach signals, not for tach signals that
vary their time between pulses during an engine cycle. Use the input 1 RPM functions
instead.
Please refer also to appendix A for details on different speed or rotational sensors.
10. Measuring duty cycle
To measure the duty cycle of a signal in channels 3, 4, and 5, the input signal must cover the
same voltage range as for a frequency signal. Duty cycle is defined as the ratio between the time
a signal is active and the total time of the active and inactive time. A signal can be either active
high ( the event, like injector open, happens when there is a high voltage) or active low (the event
happes when the measured signal is at ground or close to it).
Very often the injector duty cycle is to be measured by the DL-32. A typical fuel injector is
connected to 12V on one side, while the other side is connected to ground when the ECU opens
the injector. Because the pulse is therefore active when the voltage on the pin is at ground,
negative duty cycle is measured.
So called peak-hold injectors (as opposed to saturated injectors), work differently. Their drive
signal first goes to ground for a high current opening pulse, then rises to 8-10 Volts for the hold
period. Because the DL-32 sees everything above 2.5V as “high”, it will be able to see only the
peak period. On some peak-hold systems it is possible to connect the CHx+ input of the DL-32 to
12V at the injector and connect the CHx- input to the injector signal to still measure correctly. But
that is not always the case. The LogWorks 2.0 Manual shows an alternative method. If the above
method works, it actually measures positive duty cycle.