Campbell Scientific SDM-INT8 8-Channel Interval Timer - Manual (Page 18)

SDM-INT8 8 Channel Interval Timer
6 - Low resolution frequency (kHz)--
For this function to return low resolution data, it must be the only function
used in the instruction. If this is not the only function used in the
instruction, it returns high resolution data, the same as Function 2.
Higher frequencies may be measured if fewer channels are used (see
Section 2, Specifications).
For this function, any data value less than 1 is returned as 0. This must be
considered when calculating the multiplier and offset (Parameters 8 and
9).
The frequency is returned to the datalogger in a low resolution format (16
bit floating point). This format allows for a range of positive real
numbers between 1 and 65480 with 4 digit resolution on values whose
mantissa is less than 8192. Three (3) digit resolution is given on values
with mantissas greater than or equal to 8192.
Fewer bits are transferred to the datalogger in the 16 bit format, speeding
up the instruction execution time by 0.3 ms per value.
7 - Counts--
"Counts" will always return an integer value when Instruction 101 is
executed. The value will be the number of edges that have occurred since
the last execution of Instruction 101. If no edges have occurred, a zero is
returned. This function does not work with the Capture All Events
Output Option.
If counts are being totalized by the datalogger, use the Continuous
Averaging Output with "Counts" to avoid missing any counts (Section
5.4).
8 - Integral counts on chnl 2 since chnl 1--
Same as function 5 with no linear interpolation.
Example: The INT8 is used in an automotive test to measure crank
angle, engine RPM when spark #1 fires, and fuel injector duty cycle.
Parameters 2 and 3 are programmed as follows:
Parameter 2:0001 (channels 8,7,6,5)
Parameter 3:0000 (channels 4,3,2,1)
Channel 1: crank shaft reference pulse, rising edge (0)
Channel 2 pulse from the flywheel teeth, rising edge (0)
Channel 3: pulse from spark #1, rising edge (0)
Channel 4: fuel injector pulse, rising edge (0)
Channel 5: fuel injector pulse, falling edge (1)
Parameters 4 and 5 are programmed for the following functions:
Parameter 4:0003 (channels 8,7,6,5)
Parameter 5:2502 (channels 4,3,2,1)
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