Innovate Motorsports LM-1 RPM Converter (Aux. Input Cable 2) - Manual (Page 8)

6. RPM Converter Specification
Min
Typical Max Unit
Measurable RPM (Note1) 100 10,230 RPM
Input frequency 0.8 1100 Hz
Input Pulse Amplitude 1.5 250 V
Input Impedance (RPM input) 10 kOhm
Input Impedance (Aux inputs) 2 MOhm
Minimum Input pulse width 0.1 usec
Measurement error (Note 2) 1.0 % of indicated
Resolution (Note3) 10 RPM
RPM-output rise/fall time 0.04 sec/1000
RPM
Overswing 20 RPM
Power consumption (5V) 10 mA
Cable Length 6 ft.
Housing Size (LxWxH) 4.175 x 1.75x0.6 in.
Note1: When calibrated with 4000 RPM instead of 2000 RPM, max RPM is 20,460.
Note2: or 50 RPM, whichever is greater.
Note3: When calibrated with 4000 RPM instead of 2000 RPM, resolution is 20 RPM.
7. Auxiliary Inputs
The Auxiliary Inputs of the RPM-Converter cable or the Aux Input cable are used to connect other
signals from the car to the LM-1 for data logging. The procedure is the same for all inputs.
When connecting signals to the Auxiliary inputs, connect the Ground of the Aux Input Cable (or
RPM converter) as close as possible to the sensor from which you want the highest resolution.
Ground differences between sensors can falsify the results. Ground differences can be as large
as 0.5V, which is 10% of the input range. The Auxiliary inputs have an input impedance (static) of
greater than 1 MOhm.
You can only hook up Aux-input signals whose voltage never
exceeds 5 V and does not go below ground. Failure to heed this warning
may cause irreparable damage to either the LM-1 or the RPM-converter.
Typical sensors like MAP sensors or TPS sensor output signals vary with the measured quantity.
If the Aux Inputs are used to measure switched signals involving coils like solenoids or relays,
special protection devices should be added. The following example describes using an Aux
Input to record the state of a NOS solenoid. The same protection method can be used for other
solenoids or relays or other switched signals that exceed the 5V input limit of the Aux inputs.