Glossary
Glossary-7
Programmable Logic Controllers S7-300 Module Data
A5E00105505-03
Optically isolated
With optically isolated input/output modules, the reference potentials of the con-
trol and load circuit are galvanically isolated; for example, by an optocoupler,
contact assembly or repeater. Input/output circuits can be connected to common
potential.
Organization block
Organization blocks (OBs) form the interface between the operating system of
the CPU and the user program. The order in which the user program is pro-
cessed is defined in the organization blocks.
Parameters
1. Tag of a → Logic block
2. Tag for setting the characteristics of a module (one or more per module).
When delivered to the customer, each module has a practical basic setting for its
parameters, which the user can modify in STEP 7.
Process image
The signal states of the digital input and output modules are stored in the CPU in
process image.
A distinction is made between the process-image of inputs and of outputs. The
process input image (PII) is read by the input modules before the operating sys-
tem scans the user program. The process output image (PIQ) is transferred to
the output modules at the end of program scanning.
Product status
Products having an identical order number are distinguished by their product sta-
tus. The product status is incremented for upwards compatible extensions, modi-
fications due to production reasons (use of new component parts and compo-
nents) and troubleshooting.
Programming device
→Programming device
Programming device
A programming device (PG) is a personal computer in a specific industry-stan-
dard and compact design. A PG is completely equipped for programming
SIMATIC programmable logic controllers.
Reaction to open thermocouple
Parameter in STEP 7 for analog input modules when using Thermocouples. This
parameter defines whether “Overflow” (7FFF
0H
0) or “Underflow” (8000
0H
0) is
output by the module in the event of an open thermocouple.
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