Section 5. Overview
Measuring the resonant frequency by means of period averaging is the classic
technique, but Campbell Scientific has developed static and dynamic spectral-
analysis techniques (VSPECT
(p. 521)) that produce superior noise rejection, higher
resolution, diagnostic data, and, in the case of dynamic VSPECT, measurements
up to 333.3 Hz.
SE terminals are configurable for time-domain vibrating wire measurement,
which is a technique now superseded in most applications by VSPECT
(p. 521)
vibrating wire analysis. See Vibrating Wire Input Modules — List (p. 563) for more
information
Dynamic VSPECT measurements require addition of an interface module.
5.2.6 Reading Smart Sensors — Overview
Related Topics:
• Reading Smart Sensors — Overview (p. 74)
• Reading Smart Sensors — Details
(p. 384)
A smart sensor is equipped with independent measurement circuitry that makes
the basic measurement and sends measurement and measurement related data to
the CR800. Smart sensors vary widely in output modes. Many have multiple
output options. Output options supported by the CR800 include SDI-12
(p. 240),
RS-232
(p. 279), Modbus (p. 436), and DNP3 (p. 436).
The following smart sensor types can be measured on the indicated terminals:
• SDI-12 devices: C
• Synchronous Devices for Measurement (SDM): C
• Smart sensors: C terminals, RS-232 port, and CS I/O port with the
appropriate interface.
• Modbus or DNP3 network: RS-232 port and CS I/O port with the
appropriate interface
• Other serial I/O devices: C terminals, RS-232 port, and CS I/O port with
the appropriate interface
5.2.6.1 SDI-12 Sensor Support — Overview
Related Topics:
• SDI-12 Sensor Support — Overview (p. 74)
• SDI-12 Sensor Support — Details (p. 385)
• Serial I/O: SDI-12 Sensor Support — Programming Resource (p. 240)
SDI-12 is a smart-sensor protocol that uses one input port on the CR800 and is
powered by 12 Vdc. Refer to the chart CR800 Terminal Definitions
(p. 58), which
indicates C terminals that can be configured for SDI-12 input.
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