Siemens SIMATIC S7-400 Reference Manual page 451

Each input channel to which the reference junction "RTD on channel 0" is assigned has the
reference channel error in the situation described above - the measured temperature is no
longer compensated.
Reference junction
Parameter in STEP 7 for analog input modules. This parameter specifies the reference point
(point with known temperature) when using the thermoelements. Reference points can be:
Thermoresistor on channel 0 of the module; → compensating box, → reference temperature.
Reference potential
Potential on the basis of which the voltages of the circuits involved are measured.
Reference temperature
Parameter in STEP 7 for analog input modules. The reference temperature is the temperature
of the reference junction of thermoelements. The reference temperature allows correct
temperature measurement with thermoelements. The temperature of the reference junction
must be known because a thermoelement always detects the temperature difference between
the measuring point and the reference junction.
Repeater
Device for amplifying bus signals and for linking → bus segments over long distances.
Repetition accuracy
The repetition accuracy is the maximum deviation of the measured/output values when the
same input signal is applied or the same output value is specified repeatedly. The repetition
accuracy relates to the nominal range of the module and applies to the settled state (in terms
of temperature).
Resolution
With analog modules, this is the number of bits that represent the digitalized analog value in
binary format. The resolution depends on the module and, with analog input modules, on the
→ integration time. The longer the integration time, the more precise the resolution of the
measured value. The resolution including sign can be up to 16 bits.
Retentive memory
Data areas in data blocks along with timers, counters and bit memory are retentive when their
content is retained through a warm restart or power cycle.
S7-400 Automation System Module Data
Reference Manual, Ausgabe 11/2016, A5E00850736-08
Glossary
451