Campbell Scientific SDM-INT8 8-Channel Interval Timer - Manual (Page 24)

SDM-INT8 8 Channel Interval Timer
Since the number of values returned may be variable, making it difficult to
assign a fixed number of input locations, the Capture All Events Option
outputs data directly to the datalogger's Final Storage when Instruction 101 is
executed.
If the Output Flag is not set when the instruction is executed, the datalogger
commands the INT8 to start measuring, and no results are returned. If the
Output Flag is set, the datalogger retrieves the events that have been stored
since the last time the instruction was executed and stores them directly in
Final Storage. Data from the lowest numbered programmed channel are output
first. Each subsequent channel's output has a new array ID which is
incremented by 1. When all data are transferred, the INT8 starts its measuring
process again.
The INT8 waits for the first edge on channel 1 as a "trigger" to start making
measurements. It will then capture edges until XXXX edges on channel 1, or
until the datalogger again addresses it, or until 8000 edges have been captured,
whichever happens first. Output will not be returned until Instruction 101 is
executed with the Output Flag set, even if the edge limits are reached.
With this option, Instruction 101 does not have to be executed every 16.77
seconds. The INT8 will continue to measure without entering the low power
mode until 8000 edges are captured. Events being measured by the INT8 must
not exceed 16.77 seconds, or false measurements will be returned. The
maximum input is 10 kHz for all channels.
On a 10 second one-shot test, for example, Instruction 101 could be executed
with the Output Flag cleared and then executed 10 seconds later with the
Output Flag set. Or, Instruction 101 could be placed in a subroutine and called
from different points in the programs.
For a 10 second test repeated every 10 seconds, the Output Flag could be set
every time the instruction is executed.
Analog measurements can be made by the datalogger while the INT8 is
capturing events. To some degree, and with caution, datalogger measurements
can be synchronized with INT8 measurements. For example, the datalogger
can execute the Burst Mode after executing Instruction 101 and trigger on the
same signal that triggers channel 1 of the INT8. The caution is that the trigger
on channel 1 cannot occur before the datalogger has a chance to enter the Burst
Mode. To synchronize datalogger and INT8, the Burst Mode should be ready
and waiting for the "trigger".
6.4.6 Option 9999--: Test Memory
Option 9999-- causes the INT8 to do a self memory test instead of measure
and process timing functions. The signature of the INT8 PROM is returned to
the datalogger's Input Location of the initial execution of the instruction. If the
value is negative it indicates bad RAM; 0 indicates a bad PROM, as shown in
Table 5.
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