Siemens SIMATIC S7 Manual page 60

P
Parameter
Parameterization
Procedure
Process image
Protocol
R
Rack
S
Server
Software
START UP
STEP7
Subnet
System Block
System Function (SFC)
System Function Block (SFB) System function blocks are software modules with memory which are
MODBUS / TCP communication via the integrated PN interface of the CPU
2XV9450-1MB02; Manual edition 2.1
Parameters are values that can be assigned. A distinction is made
between block parameters and module parameters.
Parameterization means setting the behavior of a module.
The execution of a data interchange operation according to a specific
protocol is called a procedure.
This is a special memory area in the PLC. At the beginning of the cyclic
program, the signal states of the input modules are transferred to the
process image input table. At the end of the cyclic program, the process
image of the outputs is transferred to the output modules as output
signals.
The communications partners involved in a data interchange must
abide by fixed rules for handling and implementing the data traffic.
These rules are called protocols.
A rack is a rail containing slots for mounting modules.
A server is a device, or in general terms, an object that provides certain
services. A service is started at the instigation of a -> client.
Software is the term given to all programs used on a computer system.
These include the operating system and the user programs.
The operating mode START UP is active when the PLC transits from
operating mode STOP to operating mode RUN.
STEP7 is the programming software of SIMATIC S7.
A subnet is part of a -> network whose parameters must be matched.
The subnet includes bus components and all the attached stations.
Subnets can, for example, be connected together by -> gateways to
form a network.
A system consists of several subnets with unique subnet numbers. A
subnet consists of several stations with unique -> MAC addresses.
System blocks differ from the other blocks in that they are already
integrated into the S7-400 system and are available for already defined
system functions. They are classified into system data blocks, system
functions, and system function blocks.
System functions are software modules without memory which are
already integrated into the operating system of the S7-PLC and can be
called by the user as required.
already integrated into the operating system of the S7-PLC and can be
called up by the user as required.
Glossary - 4