Greenfield
Factory Automation
Bassett
Batch Processing
Hand
Process Automation
Reynolds
Packaging Automation
Campbell
On the Edge
Factory & Machine Automation Playbook cover
This one-of-a-kind Factory Automation Playbook is packed with best practices, practical tips and pitfalls to avoid on a wide range of topics, from defining project objectives to selecting components to implementing technologies that can make your automated systems smarter and more productive.

 

Tech Abstract
|

Electronic Marshalling Overview

Print Reprint
Summary: This 16-page white paper discusses electronic marshalling—eliminating “cross-marshalling” to wired discrete and 4-20mA devices—for brownfield and greenfield projects, as well as adding controllers and input/output (I/O) devices can be done with less complexity. The paper cites late change orders around I/O requirements, more aggressive schedules, sequential execution of projects and new technology learning curves—“the complexity paradox”—as prime examples of how projects have become more complex.
Inevitably, I/O has to be added or changed late in a project. Maybe a pressure switch gets changed to a pressure transmitter, so a discrete input needs to be changed to an analog input. Or, maybe a skid has not been accounted for and suddenly the system has to accommodate for a number of new I/O points and a controller with spare I/O capacity has to be found.

With this scenario, delays can happen to increase the risk associated with a project.  Many I/O changes, or sometimes for other reasons, it is necessary to split up a controller, which can cause additional delays to the project. A controller may have to be split if more I/O is required, but no single controller can handle the new I/O. This means that configuration and I/O for process equipment has to be moved from one controller to a new one.

Control configuration is usually easy to reassign to a new controller, but physically moving I/O cards and cross marshalling can be more complex. First of all, if I/O that has already been cross-marshalled needs to be moved to another controller, the multi-core cables from the field have to be moved from one marshalling panel to another. Then, the cross-marshalling has to be redone, which causes costly delays. This may also increase the need for panel space.

Electronic marshalling
As in wired marshalling, the multi-core cables from the field still land on the right side of the terminal blocks in the marshalling cabinet, so there are no changes to the work done by technicians that wire up the multi-core cables from the field. However, there are no cross-marshalling wires; all of the work, design, and engineering associated with cross-marshalling simply go away, because each individual I/O channel will be Electronically Marshalled to any controller in the system. This means that the I/O can be bound to specific controllers at any stage in the project. If late changes are made to I/O types, or new I/O is added, no adjustments to existing wiring or the cabinets must be made. New I/O can be added to the marshalling cabinets and electronically marshaled to the controllers that need the I/O.

Components
CHARacterization Modules (CHARMs) are the components involved with Electronic Marshalling that allow the late characterization of any type (AI, AO, DI, DO, RTD) of I/O signal. A CHARM is simply a component that includes a passive A/D converter and signal characterizer. CHARMs that are inserted onto the terminal block where field wires are landed. In fact, landing of field wires is much more forgiving, because the wires can be anywhere on the strip‘, without regard to a particular order or type of I/O. So, if wires for the following signals are landed: AI, AI, DI, DO, AO, DI, DO down the terminal strip, that is fine. After wiring, the technician sees the first channel is an AI, reaches into the bag of AI CHARMs, clicks in the CHARM and is done.

Link to the full version of this white paper at bit.ly/awtech004

This white paper was written by Emerson Process Management. Publication Date: February 2011 

COMPANIES IN THIS ARTICLE: Emerson Process Management

0

Add new comment

 

  NEWSLETTERS
Don’t miss intelligence crucial to your job and business!
Click on any newsletter to view a sample. Enter your email address below to sign up!

News Insights

News & Analysis

Product Insights

Latest Automation Products

Best of Blogs

Industrial Automation Columnists

Automation Focus

Sponsored white papers, videos and products

Continuous Processing

Oil & Gas, Chemical and More

Automation Skills

Improve Industry Skills

Industrial
Ethernet Review

Network Application of IE

Factory Automation

Technology for Discrete Manufacturing

Food Bev & Pharma

Automation Applications & Trends

Global Edition

Global automation news

Each newsletter ranges in frequency from once per month to a few times per month at most.

 

The best of the essentials!
Secrets to Automation Project Success

Sign up to receive timely updates from our editors and download this FREE Automation Project Survival Guide. It’s packed with field-tested best practices from industry experts that can help make your next automation project a success.

x