Tag Archive: DCS

May
19

Update – Providing 24VDC to Field Devices

3 Wire Terminal Block

In a blog posted late last month I addressed how to provide a 24VDC source of power to a three wire field device. In the past I have used a 24VDC High Side Discrete output to provide  24VDC to these types of devices. This solution can be  implemented in most DCS and PLC systems. If …

Continue reading »

May
05

Control Loop Foundation Reprint

Manual Tuning Integrating Process

A book goes through many reviews and edits before it can be published. Still, it is very difficult for the authors and reviewers to catch all the typo’s in the original text and those that are introduced during the type setting process (formatting for publication). ISA recently notified me that the book that Mark Nixon …

Continue reading »

Apr
28

Providing 24VDC to Field Devices

OLYMPUS DIGITAL CAMERA

Some field devices such as an inductive proximity switch may be designed as three wire devices that require a 24VDC source of power. In such cases it is possible to tap into the 24 volt bulk power supply in the rack room and run twisted pair to the device. However, to protect against a short …

Continue reading »

Apr
21

IEC 61987 – List of Properties (LOP)

IEC List of Properties Standard 61987

During the TC65 Plenary meeting each working group gives an activity report that summarizes the status of standards that are being developed or updated. At the Hamburg meeting, March 31- April 4th I was a delegate to the SC65B and SC65C meeting and lead the US delegation in the SC65E meeting. The reports by Peer …

Continue reading »

Feb
11

Control Utilization

Pulp and Paper Mill Control Utilization

It can be shocking to examine control utilization in a plant where performance tools have not been installed and/or not used. For example, in the mid-1980s a control survey was conducted at a major pulp and paper plant where the control system had recently been updated to the latest distributed control system. At that time …

Continue reading »

Jun
25

Distributed Control Systems’ Implementation of Mode

PID-Faceplate-Detail

To ease operator transition from panel-based systems to monitor-based systems, the manner in which first generation Distributed Control Systems (DCS) displayed information often mimicked the way this information had earlier appeared on the control panel. Since the control interface provided by the control panel was familiar and had proven to be effective, a similar presentation …

Continue reading »

Mar
05

Control Using Wireless Devices – The Challenge

Traditional Control Execution and Measurement Update

There are significant difference in the frequency and manner in which anew measurement value is updated by a wired transmitter vs. a wireless transmitter. Thus, it is natural to question what impact this has whena wireless transmitter is used in closed loop control. Since most wireless transmitters are battery powered, it is desirable to minimize …

Continue reading »

Feb
08

Virtualization – Real Today, a Reality Tomorrow

Virtualization technology has advanced a lot over the past 10 years. Most IT organizations now make extensive use of virtualization technology to consolidate servers and manage very large numbers of users. Virtualization provides a much improved architecture for isolating applications from hardware changes, securing systems, providing patch management, and improving power management (in large data …

Continue reading »