Glossary
S7-300 Automation System Module data
Manual, 08/2006, A5E00105505-04
Glossary-9
Substitution value
Values output by faulty signal output modules to the process, or used to substitute a process
value of a faulty signal input module in the user program.
Substitution values are configurable in STEP 7 (hold last value, substitution value 0 or 1.)
Those values must be set at the outputs when the CPU goes into STOP.
System diagnostics
Denotes the detection, evaluation and reporting of error events within the automation
system. Examples of such errors are: program errors, or module failure. System errors may
be indicated by LED displays, or in
STEP 7
.
System Function
A System Function (SFC) is an integral function of the CPU operating system, and can be
called in the STEP 7 user program as required.
Temperature coefficient
STEP 7
parameter for analog input modules, for temperature measurements taken with
resistance thermometers (RTD.) The selected temperature coefficient is specific to the
resistance thermometer being used (to DIN standard.)
Temperature error
Denotes the drift of measured/output values, caused by fluctuation of the ambient
temperature at an analog module. It is defined in % per Kelvin, relative to the rated range of
the analog module.
Temperature error of internal compensation
Only applies to the measurement of thermocouples. Defines the error to add to the actual
temperature error, when "internal comparison" mode is selected. The error is defined either
as a percentile value relative to the physical rated range of the analog module, or as an
absolute value in °C.
ungrounded
no galvanic connection to ground potential
User program
Contains statements, tags and data for processing signals which can control a plant or
process. It is assigned to a programmable module (CPU, FM, for example) and can be
organized in smaller units (blocks).
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