Campbell CS475, Instruction Manual

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C-1
Appendix C. SDI-12 Commands/
Changing Settings
The SDI-12 commands are entered using the 25616, Adjustment/Display
Module , or the terminal emulator in LoggerNet or PC400 (see Appendix C.2 ,
Using Terminal Emulator and a Datalogger to Send Commands
(p. C-9)
). These
commands are also used in CRBasic or Edlog programming (see Section 7.4 ,
Datalogger Programming
(p. 14)
).
SDI-12 commands have three components:
•
Sensor address (a) – a single ASCII character, and is the first
character of the command. The sensor address allows multiple sensors
to be connected to a single control port. The default address is zero,
and typically is only changed when multiple sensors are connected to
the same port. Valid addresses are 1 to 9, A to Z, or a to z.
• Command body (e.g., M1)
– an upper case letter (the “command”)
followed by alphanumeric qualifiers.
•
Command termination (!) – an exclamation mark.
An active sensor responds to each command. Responses have several standard
forms and terminate with <CR><LF> (carriage return – line feed). SDI-12
commands supported by the radar sensors are listed in TABLE C-1 .
TABLE C-1. SDI-12 Commands
Function SDI-12 Command
Address Query ?!
Send Identification aI!
Acknowledge Active a!
Change Address aAb!
Where a is the current address and b is the
new address.
Start Verification aV!
Start Measurement aM!
Start Measurement and Request
CRC
aMC!
Send Data aD0!...aD9!
Additional Measurements aM1!...aM9!
Additional Measurement and
Request CRC
aMC1!...aMC9!
Start Concurrent Measurement aC!