Page 4 - Serial Data Transmission and KNX Protocol

KNX TUTOR SEMINAR

1 Fundamentals of Serial Data Transmission

1.1 Introduction and Terminology

1.1.1 Hierarchical Problem Division
Hierarchical division expediently solves the variety of tasks that arise from the automation
of machining or operational procedures. The hierarchical levels take on the following
tasks for example:

Main computer: All Manufacturing (or Material) Requirements Planning
(MRP) and Production Control is done at this stage. This is,
among other things, manufacturing planning resulting from
requirements for production planning / scheduling as well as
central production control. It is therefore necessary to feed
condensed production-specific data from the process level
back to the main computer.

Process computer/ These control one section of the
Control centre: manufacturing process. In car manufacturing, such plant
sections could be the car body production line, the paint line,
the assembly of the drive mechanics, etc. The process
computer is responsible for data acquisition and
compression, for monitoring and optimisation.

Field level: This could for example be a programmable (logic) controller
(PLC) with all the sensors and actuators, or intelligent
sensors and actuators, connected to it.

1.1.2 Hierarchical Structures

The hierarchical division of tasks leads to the hierarchical structure of the communications
networks used in plants and installations. The demands made on the network are
different at each level.

The operations level handles large data volumes but on the other hand requires no time-
critical data transmissions. Relatively small amounts of data are processed on the field
level but uncontrollable delays in data transmission cannot be tolerated at this level of the
automated installation.

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