Xylem H-310 - Manual (Page 27)

Appendix C
SDI-12 Command and Response Protocol
H-310
Appendix C SDI-12 Command and Response Protocol C-1
C.1 SDI-12 Command and Response Protocol
This is a brief description of the Serial Digital Interface (SDI-12) Command and Response
protocol used by the W
ATER LOG ® H-310 sensor. Included is a description of the commands and
data format supported by the H-310.
Refer to the document "A SERIAL DIGITAL INTERFACE STANDARD FOR HYDROLOGIC
AND ENVIRONMENTAL SENSORS" for a complete description of the SDI-12 protocol.
Version 1.0 October, 1988 Coordinated by Campbell Scientific, Inc., Logan, Utah.
During normal communication, the data recorder sends an address together with a command to
the W
ATER LOG ® H-310 sensor. The H-310 then replies with a "response". In the following
descriptions, SDI-12 commands and responses are enclosed in quotes. The SDI-12 address and
the command/response block terminators are defined as follows:
"a" Is the sensor address (0-9,*).
0 Is the default sensor address. Sensors will be initially programmed by the factory for this
address for use in single sensor systems.
1 - 9 Are addresses for additional sensors connected to the same SDI-12 bus.
A - Z Are additional addresses supported by the H-310.
* Is a printable ASCII "wild card" address which selects any sensor, regardless of its actual
address. This address is unique to the H-300, H-310 and H-350 sensors manufactured by
Design Analysis.
"!" Is the last character of a command block.
"" Are carriage return (0D)hex and line feed (0A)hex characters. They are the last two
characters of a response block.
Notes:
All command/responses are upper-case printable ASCII characters.
Commands must be terminated with a "!" character.
Responses are terminated with characters.
The command string must be transmitted in a contiguous block with no gaps of more
than 1.66 milliseconds between characters.
All ASCII-Hex commands, arguments and data values are transmitted
most-significant-digit first.