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*OC*
Open circuit.
*NA*
Telemetry data not received.
*LO*
Temperature measured was below the range of the logger.
*HI*
Temperature measured was above the range of the logger.
***
Calculation cannot be performed (not necessarily because the data are invalid). Does
not appear in View Data analysis mode.
Probes with an intermittent open circuit may produce spiky, erratic profiles.
Note that spikes are inevitable when probes are disconnected from a running
data logger. Typical causes of invalid or interrupted data are:
Thermocouple becoming detached from the logger.
Faulty connection.
Readings which are inconsistent with those of other probes may be caused by a
short circuit (see 'Logger Diagnostics', below). The probe concerned must be
replaced.
Logger Diagnostics
Running the data logger diagnostics provides information on the status of the
logger and the means to test the thermocouple probes. Short circuits and open
circuits may be revealed: these are sometimes intermittent, and can be a
function of temperature and/or rate of change of temperature, or caused by
bending the probe cable.
1. Connect the logger to the PC (to minimize communications problems,
connect the lead first to the PC and then to the logger). The red LED on
the logger should flash five times to confirm that the connection between
the communications lead and the logger has been made.
2. Connect a full set of thermocouple probes to the logger, leaving them at
ambient temperature.
3. On the Insight software's menu bar, select Logger > Comms Setup to open
the Communications Setup dialog.
4. Click Test.
5. If the logger is detected, the Diagnostic section of the dialog appears (see
p. 22). The Temperature list box identifies all available probe channels, the
indicated temperature or status, and the temperature of the internal cold
junction.
6. Check that all probes are indicating the same temperature. Replace any
showing *OC* (open circuit), or having inconsistent readings indicating an
intermittent short circuit.
7. Place the probes into a bowl of hot water and check that all probes show a
similar increase in temperature. Replace any showing ambient temperature
as this indicates a short circuit. If any probe shows a temperature
34
Troubleshooting
DATAPAQ XDL12
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