62 Troubleshooting DATAPAQ TP3
To minimize communications problems:
• Connect the lead first to the PC and then to the logger.
• Always use the same USB port – the one which was first used to set up
communications (p. 39).
Checking the Data
If you suspect that invalid data may have been introduced into your
temperature profile (paqfile), perhaps by damaged thermocouples (see below),
select the View Data tab in Insight’s Analysis Window to view the raw data as
downloaded from the logger. The various types of invalid data which may be
contained in a paqfile are shown in the analysis grid as follows.
*OC* Open circuit. Will occur if recording starts before thermocouples are plugged in.
*NA* Telemetry data not received. Check antenna connectors.
*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 of invalid data. Does not
appear in View Data analysis mode.
Typical causes of invalid or interrupted data are:
• Damaged thermocouple cable.
• Thermocouple becoming detached from plug/logger.
• Faulty connection at thermocouple’s hot junction.
Readings which are inconsistent with those of other thermocouples may be
caused by a short circuit (see below). The thermocouple concerned must be
replaced.
Open circuit readings can occur during a profile run if a thermocouple
becomes damaged. The logger will then continue sampling on that channel, but,
by default, an alarm will be registered. For further details of such alarms, or to
disable the alarm, select Tools > Options > Run Alarms.
Thermocouples with an intermittent open circuit may produce spiky, erratic
profiles. Note that spikes are inevitable when thermocouples are disconnected
from a running data logger.
Testing the Logger and Thermocouples
Although thermocouples are generally robust, they can be damaged during
handling. Use the following procedure to confirm the operation of logger and
thermocouples after installation. Note that this test is not an alternative to
calibration (p. 33), but will highlight a malfunctioning logger or faulty probes
and thus avoid a wasted profile run.
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