4. An Entering SDI12 Terminal response indicates that SDI-12 transparent mode is
active and ready to transmit SDI-12 commands and display responses.
22.9.2.1 Watch command (sniffer mode)
The terminal-mode utility allows monitoring of SDI-12 traffic by using the watch command
(sniffer mode). Watch an instructional video:https://www.campbellsci.com/videos/sdi12-sensors-
watch-or-sniffer-mode or use the following instructions.
1. Enter the transparent mode as described previously.
2. Press Enter until a CR300 series> prompt appears.
3. Type W and then press Enter.
4. In response, the query Select SDI12 Port: is presented with a list of available ports.
Enter the port number assigned to the terminal to which the SDI-12 sensor is connected,
and press Enter.
5. In answer to Enter timeout (secs): type 100 and press Enter.
6. In response to the query ASCII (Y)?, type Y and press Enter.
7. SDI-12 communications are then opened for viewing.
22.9.2.2 SDI-12 transparent mode commands
SDI-12 commands and responses are defined by the SDI-12 Support Group (www.sdi-12.org )
and are available in the SDI-12 Specification . Sensor manufacturers determine which
commands to support. Commands have three components:
l
Sensor address ( a): A single character and the first character of the command. Sensors are
usually assigned a default address of zero by the manufacturer. The wildcard address ( ?) is
used in the Address Query command. Some manufacturers may allow it to be used in
other commands. SDI-12 sensors accept addresses 0 through 9, a through z, and A through
Z.
l
Command body (for example, M1): An upper case letter (the “command”) followed by
alphanumeric qualifiers.
l
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).
22. Tips and troubleshooting183
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