1 Introduction
1.1 Purpose
There is often a need to transfer data between controllers from different manu-
facturers or exchange them with a higher level host computer. Each system has its
own transfer protocol. Implementation of an alien protocol is often impossible or
only possible at great cost. This results from the following background
conditions:
The interface drivers do not match
The interface controller does not meet the requirements
Insufficient or lacking computer power
Real time requirements cannot be fulfilled
No facility for making additional configuration data available
Missing or insufficient commissioning and diagnosis aids
In some cases, the protocol is only required for a single system. Nevertheless the
implementation has to satisfy extreme quality demands. The effects of a software
error in the transfer protocol can lead to faults ranging up to the standstill of the
entire system and thus cause unpredictable costs.
Experience shows that implementation testing and inspection in particular only
take place in the laboratory or on a system which is hardly capable of
functioning. In spite of the greatest possible care, it then happens that an error on-
ly becomes apparent when the plant is in service. Particularly when the error oc-
curs sporadically or depends on particular plant conditions, location of the error
without an integrated diagnostic function is a matter of luck.
Practical experience shows that most problems are created not by errors in the
implementation but by inadequate agreements on the user level. Message mat-
ching between the linked units is in some cases incomplete or is not complied
with. As a result, messages which have not been sent are expected, or messages
are sometimes mixed up. If the message traffic can be transcribed, the problem
can be rapidly rectified.
The protocol converter is a device developed specifically for these problems,
whose operating system provides all functions necessary for the rational and re-
liable implementation of coupling protocols.
The device is supplied in various versions. The protocol converter PKV 30-DPS
has two communications interfaces and one of them is for PROFIBUS-DP slave
and the other one is for general protocols.
Introduction
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