Campbell Scientific CS650 and CS655 Water Content Reflectometers - Manual (Page 49)

Appendix B. SDI-12 Sensor Support
Aborting a Measurement Command
A measurement command (M!) is aborted when any other valid command is
sent to the sensor.
Send Data Command (aDv!)
This command requests data from the sensor. It is normally issued
automatically by the datalogger after measurement commands aMv! In
transparent mode, the user asserts this command to obtain data. If the expected
number of data values are not returned in response to a aD0! command, the
data logger issues aD1! The limiting constraint is that the total number of
characters that can be returned to a aD0! command is 35 characters. If the
number of characters exceed the limit, the remainder of the response are
obtained with the subsequent aD1! command.
B.2 Changing the SDI-12 Address Using Terminal
Emulator and a Datalogger
Up to ten CS650’s or other SDI-12 sensors can be connected to a single
datalogger control port. Each SDI-12 device on the same control port must
have a unique SDI-12 address. The CS650 supports addresses of 0-9, a-z, and
A-Z.
The factory-set SDI-12 address for the CS650 is 0 when the probe is ordered
with the –DS option or the last digit of its serial number when ordered with the
–VS option. The CS650 SDI-12 address is changed by issuing the aAb!
command where a is the current address and b is the new address. The current
address can be found by issuing the ?! command.
The easiest way to change the address on a CS650 sensor is with the Device
Configuration Utility and a A200 Sensor to PC Interface as described in
Section 6.4, A200 and Device Configuration Utility. However if a A200 is not
available, it is possible to change the address by connecting a single CS650 to a
SDI-12 compatible control port on a datalogger and utilizing SDI-12
transparent mode to send commands directly to the sensor.
B.2.1 SDI-12 Transparent Mode
System operators can manually interrogate and enter settings in probes using
transparent mode. Transparent mode is useful in troubleshooting SDI-12
systems because it allows direct communication with probes. Datalogger
security may need to be unlocked before transparent mode can be activated.
Transparent mode is entered while the PC is in telecommunications with the
datalogger through a terminal emulator program. It is easily accessed through
Campbell Scientific datalogger support software, but is also accessible with
terminal emulator programs such as Windows HyperTerminal. Datalogger
keyboards and displays cannot be used.
The terminal emulator is accessed by navigating to the Datalogger menu in
PC200W, the Tools menu in PC400, or the Datalogger menu in the Connect
screen of LoggerNet.
B-3