PROFIBUS PAKROHNE Messtechnik GmbH & Co. is certified by the PROFIBUS User Organisation (Nutzerorganisation e.V.)
For the automation of field units in process engineering PROFIBUS-PA is indeed state of the art. Several years of experience, including in Ex-Applications, confirms the dependability of this technology.
The wide availability of products with PROFIBUS-PA, as well as the complete general horizontal (Upstream-Process-Downstream) and vertical (from field to company master data surface) communication via PROFIBUS-DP and FMS are the impressive basis of the success story known as PROFIBUS. PROFIBUSPROcess FIeld BUS (PROFIBUS) is the result of a joint project started in 1987 by Bosch, Klöckner-Möller and Siemens.
This joint project subsequently involved a total of 13 companies and 5 universities.
PROFIBUS facilitates data exchange between devices from different manufacturers without special interface adaptations. The specifications of PROFIBUS are described in detail through levels 1, 2 and 7 of the ISO/OSI reference model. To date PROFIBUS has acquired a considerable market share and is field bus number 1 in its market segment.
PROFIBUS is a Multi-Master-System. Its controlled bus access is managed via a hybrid bus access method, that is to say Token Passing is applied decentrally and the Master-Slave principle is applied centrally
PROFIBUS in detailSince PROFIBUS is used in production, process automation, and building control engineering, there are several different optimised variants of PROFIBUS. PROFIBUS-FMS stands for Fieldbus Messaging Specification, PROFIBUS-DP for Decentral Periphery, and PROFIBUS-PA for Process Automation.
For detailed information about PROFIBUS-PA we recommend the KROHNE brochure PROFIBUS-PA networks: methods, and planning. Typical PROFIBUS-DP/PA networkThe automation structure below shows one of many possible combinations in process engineering. Here the PA variant is always converted to the DP variant.
It is also interesting that both devices - in Ex- and Non-Ex areas - can be used with HART® capable and conventional devices (4-20mA, binary inputs/outputs, etc.).
To make this more understandable, here are a few explanations of the terms used: The Master Class 1 is the automation system and assumes control and regulation tasks. It receives discontinuous measurement and status of all currently connected devices with cyclic services.
With the expanded DP functionality one or more Master Class 2 (Engineering or Operating and Monitoring Station) units are basically capable of dealing with all parameters and functions of the connected PA devices via acyclic services. 
The PROFIBUS-PA profileThe PA profile standardises the basic functions of all the different devices. The aim is to be able to easily interchange devices from different manufacturers, so that for example a replacement flowmeter will give identical readings. Not factored in the profile are such items as installed sensor length or the significance of calibration values. KROHNE devices have been developed according to the most recent profile definitions. Manufacturer independent operating toolsConfiguration, Parameterisation and diagnosis are facilitated by PROFIBUS-PA technology.
As a result, manufacturer-independent operating tools were developed so that the user need only learn the handling of one operating system. The Process Device Manager (PDM) from Siemens has become the industry standard. Suitable Device Descriptions are necessary for optimum integration in the PDM.
KROHNE devices are integrated into the PDM with full functionality. KROHNE devices with PROFIBUS-PAPROFIBUS technology used in KROHNE devices satisfies all the highest requirements. Here are a few highlights:
Highest reliability thanks to separate fault disconnect electronics
Compared with other products on the market we have placed particular value on a separate fault disconnect electronics (FDE) and do not use the communication component for limiting the current uptake. Thus the device cannot block the entire bus.
Maximal number of devices with minimal current requirements
Typically KROHNE devices use the lowest possible 10mA current and ensure that the number of devices per fieldbus segment can be maximised.
Additional I/O's
In a number of applications it makes sense to supply a power output or a binary contact alongside the PROFIBUS-PA.bus. Thus, for example, the level at the bottom of a tank can be shown via a 20mA indicator. KROHNE meters typically have additional I/O's. Exceptions, of course, are pure 2-wire meters.
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