Sensor Error Compensation (Ttf350 Dtm Adjust Function / In Hmi Lcd Display Calibrate Function); D/A Analog Output Compensation (4 And 20 Ma Trim) - ABB TTF350 Operating Instructions Manual

8.4

Sensor error compensation (TTF350 DTM Adjust function / in HMI LCD display Calibrate function)

Sensor error adjustment can be performed in the TTF350 DTM by navigating to Device /
Maintenance / Adjust / Trim low or Trim high.
For sensor error adjustment, the sensor connected to the transmitter must be brought to the
temperature at measurement start / trim low via water quench or oven. It is important to make
sure the temperature is balanced and stable.
In the DTM or LCD configuration software, check that the proper adjustment temperature has
been entered for the sensor before adjusting the sensor.
Based on the configured adjustment temperature (setpoints) and the digital temperature
measured by the transmitter, which is available after linearization in the form of HART
temperature information, the transmitter calculates the temperature deviation resulting from the
sensor error.
The temperature deviation calculated results during single point adjustment in an offset shift of
the linear characteristic output by the linearization module; the values correspond to the HART
signal or are sent to the current output.
A sensor error two-point adjustment results in a change of the offset and gradient due to the
linear temperature value characteristic output by the linearization module.
A pure sensor offset error can be corrected via the function "Set Measurement Start" or the
adjustment function "Trim low". A non-exclusively sensor offset error can, on the other hand, be
corrected only with a two-point adjustment or two-point calibration.
If you enter the temperature value for sensor 1 when adjusting for sensor error on channel 2,
then channel 2 is adjusted to the temperature value of sensor 1.
This can occur at a single point (one-point adjustment – sensor – offset – underpressure) as
well as at two points (two-point adjustment – sensor – offset and gradient correction).
8.5

D/A analog output compensation (4 and 20 mA trim)

Output compensation is used to correct errors in the power input of the superordinate system.
Analog output compensation for the transmitter can be used to modify the loop current so that
the desired value is displayed in the superordinate system.
Error compensation for the superordinate system is possible at the LRL with 4 mA or 20 mA.
(Single point error correction: Offset or two-point error correction offset + linear gradient)
D/A analog output compensation can be accessed in the HMI LCD display via the menu path
Calibrate / Analog Output / Trim 4/20mA or via TTF350 DTM via the path Device / Maintenance
/ Adjust.
Prior to analog compensation, it is necessary to determine the loop current values based on
iterative entry of current data in simulation mode; the superordinate I/O system displays exactly
4,000 mA, the LRL or 20,000 mA and the URL temperature. The current loop values are to
measured via amperemeter and to record .
Simulate the LRL or 4,000 mA +/- 16µA in D/A analog output compensation mode using sensor
simulation. Thereafter, enter the iteratively measured current at which the superordinate system
displays exactly 4,000 mA or the LRL as adjustment value. Proceed in a similar manner for the
URL or 20,000 mA.
OI/TTF350-EN
2-sensor input functionality / Dual sensor mode
TTF350 49