MAINTENANCE
Touchpoint Pro
Pt. No. 2400M2566_1_EN 58 Operating Manual
9.2 Calibrating AIM-mV Input Channels
Touchpoint Pro supports routine calibration of mV sensors. TPPR can be programmed to display calibration reminders at
calibration intervals, e.g. annually or every six months.
It is compulsory to calibrate the sensor when a channel has been newly commissioned, when the sensor bead current has
been changed, or if the system configuration has been deleted.
TPPR warns when the output from a sensor reaches 50% of its initial value and should be replaced. The First Span
calibration option is used to record the initial output level of a new sensor.
Note: The TPPR mV Analogue Input Module (AIM-mV) forms part of the catalytic bead sensor measuring circuit so all
commissioned mV channels remain in Inhibit state until they are calibrated.
Note: Details on how to carry out testing can be found in the Touchpoint Pro Technical Handbook.
9.3 Calibrating AIM-mA Input Channel Loops
Touchpoint Pro supports both gas calibration of mA sensor and loop calibration of the transmitter 4-20mA current loop.
TPPR can be programmed to display calibration reminders at calibration intervals, e.g. annually or every six months.
In general gas calibration should be carried out at the sensor, using the sensor’s inbuilt calibration. Gas calibration of a
sensor from TPPR should only be carried out on sensors without this capability.
The procedure is similar. For loop calibration the Zero and Span (4mA and 20mA) currents should be set using the
transmitter’s Force functions where available.
Note: Details on how to carry out testing can be found in the Touchpoint Pro Technical Handbook.
CAUTION
Channel calibration is compulsory after changing the bead current (or catalytic sensor) of an AIM mV channel, and
the channel stays in Inhibit until this is done.
Disable or inhibit any operations or actions that may result from gas readings before starting this test.
CAUTION
Wherever possible the TPPR mA loop should always be calibrated by forcing signal levels at the sensor /
transmitter. Any gas calibration must be carried out at the field device according to the manufacturer’s instructions.
Disable or inhibit any operations or actions that may result from gas readings before starting this test.
The Touchpoint Pro controller calibration should not be used to adjust for deficiencies in the sensor / transmitter gas
calibration. Failure to observe this can result in significant accuracy errors.
The signal voltage from catalytic sensors reduces over time. Regular recalibration is required to make allowance for
these changes.
This slow change is monitored by TPPR and is used to give the sensor life expired warning when the Span value is
≤50 % of the First Span value.
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