Campbell C477, Instruction Manual

Page: 31 / 40

Appendix B. Entering 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. These commands are
also used in CRBasic or Edlog programming (see Section 6).
During normal communication, the datalogger sends the address, together with
a command, to the sensor. The sensor then replies with a “response”.
SDI-12 command codes that are used with the radar sensor are listed in Table
B-1. The SDI-12 address and the command/response terminators are defined
as follows:
Initial Command Response
a Is the sensor address. The following ASCII Characters
are valid addresses: 0-9, AZ, a-z, *, ?. Sensors are
initially programmed at the factory with the address of 0
for use in single sensor systems. Addresses 1 to 9 and A
to Z or a to z are used for additional sensors connected
to the same port.
Where:
a is the sensor address (0-9, A-Z, a-z, *, ?)
M is an upper-case ASCII character ! Is the last character of a command block
<cr><lf> Are carriage return (0D) hex and line feed (0A) hex characters. They
are the last two characters of a response block
• All commands/responses are upper-case printable ASCII
characters. NOTES
• Commands must be terminated with a ! character.
• Responses are terminated with <cr><lf> characters.
• The command string must be transmitted in a contiguous block
with no gaps of more than 1.66 milliseconds between characters
B-1