PROFIBUS PA – for Stable Process Control

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What follows is an excerpt from the recently released White Paper entitled 6 Reasons to Give PROFIBUS PA Another Look.

Infrastructure which delivers overall stability is indispensable in the process industry, and PROFIBUS offers this level of stability for data communications in the field and at the control station. The performance features of PROFIBUS PA, which are specifically tailored to process automation, facilitate optimal solutions and enhance overall system availability.

Stable, simple installation

From the technical standpoint, installation of PROFIBUS PA is similar to 4…20mA. Two-wire shielded cable is used as the transmission medium. MBP (Manchester-encoded, Bus Powered) data transmission technology was developed specifically to meet the needs of process automation and has been standardized in IEC 61158-2. Power distribution and data transmission are implemented in a single cable. This has the following advantages when compared to traditional installations like 4…20mA:

  • Reduced cabling cost and effort
  • Compliance with market demand for very simple installations which are nevertheless safe and reliable
  • Full exploitation of the advantages offered by digital data communications right down to the field device, e.g. high-precision with no drift
  • Additional devices can easily be attached, even during ongoing operation

Continuous monitoring ensures safety

Users repeatedly confirm that PROFIBUS PA based communication just keeps running and running. There is good reason to trust PROFIBUS, but it is better to keep an eye on things nevertheless. State-of-the-art diagnostic tools have provided crucial operational support on PROFIBUS systems for many years, enhancing system availability. Data visualization on state-of-the-art user interfaces and automatic generation of reports on system and device status makes it easier to assess the possible need for service intervention.

Impending device or network failure can be detected in time and usually prevented. The network automatically raises a flag if the quality of the installation becomes degraded.

Recommended by users

In many active blogs and forums, PROFIBUS users share their views on the stability and data reliability of field installations. Some argue that 4…20mA signals can be transmitted incorrectly without an error message being generated. Incorrect process data reaching the control station is interpreted as being accurate. That is virtually impossible with a digital fieldbus like PROFIBUS PA. Transmission errors are detected and reported so that corrective action can be taken. Of course instrumentation can generate incorrect signals, but even in that case there is a higher likelihood that this type of error will be detected on a fieldbus system, as every transmitted process value has its own check if calculated correctly. Every participant in a PROFIBUS network is able to send sophisticated diagnostic data which can provide an early indication of wear and other sources of error.

–Michael Bowne

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