l
Short distance networks - a data logger can talk to another data logger over distances up
to 30 feet by connecting transmit, receive, and ground wires between the data loggers.
In a PakBus network, each data logger is assigned a unique address. The default PakBus address
in most devices is 1. To communicate with the data logger, the data logger support software must
know the data logger PakBus address. The PakBus address is changed using Device
Configuration Utility, data logger Settings Editor, or PakBus Graph software.
7.7 SDI-12 communications
SDI-12 is a 1200 baud communications protocol that supports many smart sensors, probes and
devices. The data logger supports SDI-12 communications through two modes — transparent
mode and programmed mode (see
(p. 13) for wiring terminal information).
Conflicts can occur when a control port pair is used for different instructions (
TimerInput()
,
PulseCount()
,
SDI12Recorder()
,
WaitDigTrig()
). For example, if C1 is used for
SDI12Recorder()
, C2 cannot be used for
TimerInput()
,
PulseCount()
, or
WaitDigTrig()
.
Transparent mode facilitates sensor setup and troubleshooting. It allows commands to be
manually issued and the full sensor response viewed. Transparent mode does not record data.
See
(p. 140) for more information.
Programmed mode automates much of the SDI-12 protocol and provides for data recording. See
SDI-12 programmed mode/recorder mode
(p. 106) for more information.
CRBasic SDI-12 instructions include:
l
SDI12Recorder()
l
SDI12SensorSetup()
l
SDI12SensorResponse()
See the CRBasic Editor help for detailed instruction information and program examples:
https://help.campbellsci.com/crbasic/cr6/.
The data logger uses SDI-12 version 1.4.
7.7.1 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
communications with probes.
Transparent mode may need to wait for commands issued by the programmed mode to finish
before sending responses. While in transparent mode, the data logger programs may not
7. Communications protocols
104