iii)Matching DP97 to Calibrated Sensors

It is possible to automatically match the DP97 to a Pt100 sensor with up to 10 dedicated calibration values. Such values, published in an associated certificate indicate true Ω versus °C values corresponding to accurately known reference temperatures. Up to 10 sets of values per sensor can be fed into the instrument via the RS232 interface using the associated software supplied with each version 2.1 instrument as standard.

By matching the instrument to a probe on this basis, “corrected” temperature readings are obtained directly without the need for cross- referencing to temperature/resistance tables or to the calibration certificate. This is particularly helpful when taking differential (A-B) readings.

Refer to sections 6 and 7 for details.

iv)Error Indications

The DP97 has several modes of error indication according to internal or external problems as follows:

Display

Cause

Err 1

Calibration lost (very unlikely)

Err 2

Software fault

Err 3

Broken probe connection

Err 4

RS 232 command error

BAtt

“Low” battery

Or

Over-range input

Ur

Under-range input

 

 

Only Err 1 / Err 2 would require returning the instrument to our factory.

Note: During normal operation, if a selected probe is disconnected from the instrument the display will indicate Err 3 (broken probe indication). If the same probe is re-connected, Err 3 will remain on the display until any key is pressed.

v)¾ Wire Recognition

DP97 requires a minimum of 80mΩ lead resistance (eg. 1 metre of 7 stranded 0.2 mm² wire) to recognise a 4 wire probe. Otherwise the instrument will default (perhaps incorrectly) to 3 wire mode.

If a simulator is used to apply resistance values to check or calibrate the DP97 ensure that at least 80mΩ of lead resistance exists between the simulator and the D plug.

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