Device functions
Version 2
RES-5012
Page 45
8.8.6
Calibration page
This page is first available as from firmware version 303.
The temperature controller stores the absolute calibration resistance of each channel (Calibration resistance ch.
0…7) with an resolution of 0.1 mΩ.
The calculation of the respective calibration resistance is done at the end of the AUTOCAL function
(
section 8.5.1 "Automatic zero calibration AUTOCAL (AC)" on page 25).
The initial calibration resistances (Initial calibration resistance ch. 0…7) are calculated if the Master-AUTOCAL
function is executed (
section 8.5.5 "Master AUTOCAL (MA)" on page 26).
These initial calibration resistances are the basis for the calculation of the calibration deviation. Each execution of
the AUTOCAL function will calculate both, the absolute calibration resistance and likewise the percentual calibra-
tion deviation towards the initial calibration resistance.
These values are displayed on the Calibration page.
Additionally the actual value of „passes through current transformer“ are displayed. This value can be read or
written by means of acyclic services. Set this value to the real wire passes through the current transformer for that
the absolute resistance values can be calculated correctly. This value has no influence on the calculation of the
percentual calibration deviation.
The calculation of the absolute resistance values is liable to variation and imprecision due to toler-
ances in production, to application dimensioning, to quality of cabling, to fluctuations in the power
supply, etc.
8.9
Undervoltage detection
Trouble-free operation of the temperature controller is guaranteed within the line voltage and 24 VDC supply
voltage tolerances specified in section 10 "Technical data" on page 57.
If the 24 VDC supply voltage drops below the permitted lower limit, the controller is switched to standby mode. No
more heatsealing processes take place and no more measuring impulses are generated. Normal operation is
resumed when the input voltage returns to the specified tolerance range again.
Standby mode is indicated by 0…3 °C (i.e. approx. 0 V) at the analogue output. In addition, the SA bit is set in the
status word for the cyclic output data.
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