Campbell CR1000 User Manual

Section 7. Installation
where:
5 reports the sensor SDI-12 address.
004 indicates the data will be available in 4 seconds.
10 indicates that 10 values will be available.
The command 5M7! elicites a similar response, but the appendage 7 instructs the
sensor to return the voltage of the internal battery.
aC!
Start concurrent measurement. The CR1000 requests a measurement, continues
program execution, and picks up the requested data on the next pass through the
program. A measurement request is then sent again so data are ready on the next
scan. The datalogger scan rate should be set such that the resulting skew between
time of measurement and time of data collection does not compromise data
integrity. This command is new with v. 1.2 of the SDI-12 specification.
Syntax:
aC!
Aborting an SDI-12 Measurement Command
A measurement command (M! or C!) is aborted when any other valid command is
sent to the sensor.
SDI-12 Send Data Command
Send data commands are normally issued automatically by the CR1000 after the
aMv! or aCv! measurement commands. In transparent mode through CR1000
terminal commands, you need to issue these commands in series. When in
automatic mode, if the expected number of data values are not returned in
response to a aD0! command, the datalogger issues aD1!, aD2!, etc., until all data
are received. In transparent mode, you must do likewise. The limiting constraint
is that the total number of characters that can be returned to a aDv! command is
35 (75 for aCv!). If the number of characters exceed the limit, the remainder of
the response are obtained with subsequent aDv! commands wherein v increments
with each iteration.
aDv!
Request data from the sensor.
Example Syntax:
aD0!
SDI-12 Continuous Measurement Command (aR0! to aR9!)
Sensors that are continuously monitoring, such as a shaft encoder, do not require
an M command. They can be read directly with the Continuous Measurement
Command (R0! to R9!). For example, if the sensor is operating in a continuous
measurement mode, then aR0! will return the current reading of the sensor.
Responses to R commands are formatted like responses to send data (aDv!)
commands. The main difference is that R commands do not require a preceding
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Campbell CR1000 Specifications

General

Power Requirements	9.6 to 16 VDC
Data Logger Operating System	CRBasic
Memory	4 MB
Analog Inputs	16 single-ended or 8 differential
Analog Input Resolution	13 bits
Analog Input Range	+/-2.5V
Digital I/O	8
Pulse Counters	2
Communication Ports	RS-232
Operating Temperature	-25°C to +50°C
Pulse Channels	4