Campbell Scientific SDM-INT8 8-Channel Interval Timer - Manual (Page 22)

SDM-INT8 8 Channel Interval Timer
FIGURE 4. Example of Multiple Beginnings and Endings
6.4.2 Option 0: Execution Interval Averaging
When Option 0 is selected, the result from each channel is a value averaged
over the interval since the INT8 was previously addressed. Normally this
would be the execution interval. The value returned to the datalogger is the
average at hand when the INT8 is addressed. If processing lags the
measuring/storing task, the unprocessed events are not used in the averaging
and are deleted from memory.
With Option 0, the datalogger should be programmed to execute Instruction
101 at least every 16.77 seconds while making measurements. If this period is
exceeded, the INT8 enters a low power stand by mode and events are missed.
If no event occurs during the interval, 0 is returned for frequency and count
functions, and 99999 (infinity) is returned for the other functions.
With Option 0, the INT8 ceases to capture events while it is communicating
with the datalogger and reinitializes its measurement operation afterwards.
Thus, edges that occur during this communication period (generally 2.3 ms +
1.7 ms/value) are ignored by the INT8.
6.4.3 Option 32768 or 0--: Continuous Averaging
The Continuous Averaging Option is similar to Option 0 with the following
differences:
1. The INT8 keeps capturing input edges during communication with the
datalogger. If the time required for processing is less than or equal to the
time required for measuring/storing (see Table 3), events will not be
missed.
2. The datalogger will not update the input location of a channel that has not
had an event since the last time the INT8 was addressed.
With the Continuous Averaging option, the datalogger should be programmed
to execute SDMINT8 instruction or Instruction 101 at least every 16.77
seconds while making measurements. If this period is exceeded, the INT8
enters a low power stand by mode and events are missed.
The Continuous Averaging option is designed for input frequencies or
intermittent signals that are at a slower rate than the execution interval of the
datalogger. It is also used for totalizing counts.
16