Siemens SIMATIC S5 Manual page 37

IP 265
4 General Operation
4.1 Parallel Program Execution with IP 265
Remember
In the case of conventional programmable controllers (PLCs), the user program for the control of an
overall system is processed by a CPU. The individual instructions of the CPU user program are
executed sequentially by the CPU.
The use of an FPGA in an S5-100U module makes it possible for the first time to handle process
signals in parallel and therefore very fast.
By loading memory data (contents), hardware structures similar to the hardware wiring in
SIMATIC C1, C2 and C3 systems are set up on the FPGA of the IP 265. In contrast to this, the
FPGA used in the IP 265 is programmable, i.e. the hardware connections established on the FPGA
can be "deleted" and configured again as often as desired by loading memory data.
The FPGA load data necessary for a hardware connection is defined by the user in the user
program (referred to below as the IP 265 user program).
The IP 265 user program consists of basic functions such as logic operations, counters, timers and
comparators and the connections necessary between these language elements. Both the language
elements and the connections take up memory space (resources) on the IP 265. The resources of
the IP 265 available for the language elements and their connections are limited. Only small user
programs can be processed in the IP 265.
Between the IP 265 user program and the CPU user program, there are insignificant differences
with regard to the language elements and the operands.
Note
The structure of the IP 265 user program resembles the CSF 5 method of representation
(programming of SIMATIC CPUs) of the CPU user program. The use of FPGA systems
causes slight deviations when programming the IP 265.
There are basic differences between the parallel program execution of the IP 265 user program
and the sequential program execution of the CPU user program.
Figure 4-1 shows the essential differences between sequential and parallel user program execution.
EWA 4NEB 812 6130-02a
General Operation
4-1