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

SDM-INT8 8 Channel Interval Timer
1. Overview
The 8 channel Interval Timer (INT8; see Figure 1) is a measurement module
which outputs processed timing information to a 21X, CR10(X), CR23X,
CR800, CR850, CR1000, CR3000, CR5000, or CR9000(X) datalogger. Each
input channel is programmed to detect transitions from low or high level
voltage inputs (Figure 2). Period, pulse width, frequency, counts, and time
intervals are output to the datalogger for further processing/logging.
FIGURE 2. Voltage Input Options, Edges, and Thresholds
In CRBasic, the SDMINT8 instruction is used to program and control the
SDM-INT8; in Edlog, Instruction 101 is used. These instructions, address,
command, and receive data from the INT8 through three ports on the
datalogger (see Section 3). Multiple INT8s, each with a unique address, may
be controlled by one datalogger.
The INT8 has its own processor which enables it to make measurements and
process data while the datalogger is performing other tasks. Each of the 8
channels may be independently programmed to detect either rising or falling
edges and perform the following functions (Section 5.1.3).
The INT8 can capture timing events with 1 microsecond resolution over a
maximum range of 16.77 seconds. Timing on different channels can be
compared to within ± 1 microsecond. At the same time, the datalogger can be
executing various analog measurements, but the exact time these
measurements are taken is subject to the datalogger's timing resolution.
Section 7.3 discusses the possibilities and limitations of synchronizing INT8
and datalogger measurements.
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