Innovate Motorsports SSI-4 - Manual (Page 4)

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1.1 Differential Inputs
The SSI-4’s external connections are differential. This means that each input channel has 2 input
terminals. A + terminal and a – terminal. This is to eliminate ground offsets in the signal. Many
times the ground point of a sensor is at a different ground than the SSI-4. Because an electronic
device can only measure a voltage referenced to it’s own ground, differences in grounding can
introduce measurement errors. The SSI-4 measures the sensor signal’s ground with the – input
and them measures the difference between the + and the – input. This way it “recreates” the
sensor signal’s own ground reference as if this input were referenced directly to that sensor’s
ground. The common mode rejection range is the maximum voltage this ground reference input
can differ from the SSI-4 ground.
The (–) input is NOT a ground itself. It is a ground reference input.
2. Specifications
Power
Power requirements 8-36 Volt / 50mA
1
Power reversal protection Yes
External Sensor power 5V (+- 2.5%), 300mA max.
Serial Communication
Serial Port Speed 19.2 kbit/sec
Packet/Logging Speed 81.92 msec/sample packet
Sample Resolution 10 bits (0..5V at 0.1% resolution)
Input Specifications
Number of Channels 4
Input measurement range 0..5V
CHx+ max input voltages - 22.5 Volt to +300 Volt
CHx- max input voltages - 22.5 Volt to +27.5 Volt
Common Mode Rejection
Range -22.5 Volt to +22.5 Volt
Input threshhold for pulsed
Signals 2.5V
Max Frequency 15 kHz
2
Input Impedance 1 MOhm
Temperature
Max Operating Temperature -20 to +80 deg Celsius
Mechanical
Size (W x L x H) 133 x 65 x 26 mm
Weight 114 grams
Note 1:
Supply current specified does not include external sensor current supplied by 5V output.
Note 2:
Sum of all frequency/Duty Cycle signals connected should not exceed 15 kHz.