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7 Configuration
Offset
To offset plant-specific deviations, the measured value can be corrected (offset) for each analog input
(following linearization). A positive or negative form of the correction value is added to the measured val-
ue (entering a negative correction value reduces the measured value). Typical applications include com-
pensating for the line resistance of a RTD temperature probe in a two-wire circuit.
Filter time constant
The filter time constant is used to adjust the digital input filter (2nd order filter). If the input signal changes
suddenly, approx. 26 % of the change is recorded following a period that corresponds to the filter time
constant (2 × filter time constants: approx. 59 %; 5 × filter time constants: approx. 96 %). A large filter
time constant means: high attenuation of interference signals, slow reaction to the actual measured val-
ue display, low limit frequency (low-pass filter).
Resistance Ra or Ro, Rs or Rx, Re
The overall resistance Ra + Rs + Re (or Ro + Rx) must not exceed 4000 Ω.
Resistance transmitter
Resistor/potentiometer in three-wire circuit
7.5.1
Limit value monitoring
Limit value monitoring with one or two limit values (alarm 1, alarm 2) can be activated for each analog
input. In out-of-limit cases, an alarm signal is activated. Depending on the configuration, an entry is made
in the event list or additionally in the alarm list. In the latter case, the alarm/event text is displayed in the
status bar (until another alarm occurs); the collective alarm is enabled, and the plotter trace may be dis-
played in a different color.
This limit value monitoring function is independent of the general limit value monitoring values (Config-
uration > Limit value monitoring) and available in addition to them.
108
E
Re
Rs
S
A
Ra
Rx
Ro
Resistor/potentiometer in two-wire circuit
Rx
Ro
Resistor/potentiometer in four-wire circuit
Rx
Ro
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