Siemens SIMATIC S7-400 Hardware And Installation Manual page 284

Glossary
On-Board Silicon The on-board silicon disk is a memory unit in which all or part of the
Disk software of a CPU 488-4 is stored retentively, including static data.
Operating State The SIMATIC S7 programmable controllers recognize the following
operating states: STOP, STARTUP, RUN.
Operating System The operating system of the CPU organizes all functions and
of the CPU
sequences of the CPU which are not connected to a specific control
task.
Organization Block Organization blocks form the interface between the operating system of
(OB) the S7-400 CPU and the user program. The sequence in which the
user program should be processed is laid down in the organization
blocks.
P
Parameter 1. Variable of a STEP 7 logic block
2. Variable for setting the reaction of a module (one or more per
module).
Parameters can be static or dynamic.
Parameters, In contrast to static parameters, dynamic parameters of modules can
Dynamic be changed during operation by calling an SFC in the user program, for
example, limit values of an analog signal input module.
Parameters, Static In contrast to dynamic parameters, static parameters of modules
cannot be changed by means of the user program, but only via STEP 7
(not in the RUN state); for example, input delay of a digital signal input
module.
PG
PLC
Process Image The process image is a component part of the system memory of the
S7-400 CPU. At the beginning of the cyclic program, the signal states
of the input modules are transferred to the process-image input table
(PII). At the end of the cyclic program, the process-image output table
(PIQ) is transferred to the output modules as the signal state.
Glossary-10
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Programming Device
Programmable Logic Controller
S7-400 and M7-400 Programmable Controllers, Installation Manual
C79000-G7076-C424-01