Money for nothing: Consider replacing DCS now

Orlando, FL—There’s no such thing as a free lunch? Oh, but there is, if you consider savings that can add up and pay for investments in aging distributed control system infrastructure, according to a Rockwell Automation control technology replacement expert.
By Control Engineering Staff July 31, 2007

Orlando, FL —There’s no such thing as a free lunch? Oh, but there is, if you consider savings that can add up and pay for investments in aging distributed control system infrastructure, according to a Rockwell Automation control technology replacement expert. And while performing in-kind replacements, as needed and piece by piece, is certainly an option, costs are higher and the savings aren’t as great.

“We need to think harder about how we can migrate customers from legacy distributed control systems to today’s systems,” says Mike Vernak, program manager for Rockwell Automation’s legacy DCS migration solutions program. Reasons for delaying upgrades include unwillingness to shut down production, lack of capital budgets, and an apparent willingness to spend the dollars on maintenance, he says. Vernak told Control Engineering at the company’s recent RSTechEd conference that, in his more than 20 years in process industries, he has seen similar challenges everywhere.

“I ask people how things are operating, what keeps them up at night, and what are the risks associated with unplanned downtime,” Vernak explains. Sometimes one lost batch can cost millions of dollars. Also part of the conversation are benefits that can accrue from update systems, such as the latest PC-based controllers, advanced human-machine interfaces, faster information about the process, tighter loop control, and use of advanced algorithms. Upgrades also provide the opportunity to redesign processes more efficiently, and phase a migration, if that’s needed. He said sometimes one unit will get a new DCS, and the removed equipment becomes a parts store for remaining units until capital is available to migrate the rest of the plant.

At the request of Control Engineering , Vernak assembled the table, “Legacy DCS migration cost justification,” to compare some costs of direct part replacement versus purchasing a new system. As if the 10-fold difference in replacement costs weren’t convincing enough, supporting reasons (such as lack of technical support, difficulty in finding parts, and data flow and translation challenges) help make project justification easier. See the table for more.

Direct replacement
(In-kind parts)
New peplacement
(New Microsoft-based PC)
Reasons to replace
Console replacement,

Hardware (HW) & software (SW) licenses

$50K+ $5K+
  • •Unsupported HW/SW

  • Difficult to find spare parts

  • Costly to replace/repair

  • Difficult to get data to/from

  • Lack of technical support

Controller replacement
(HW & tag licences)
$20– 40K $5– 15K
  • •Unsupported HW/SW

  • Difficult to find spare parts

  • Costly to replace/repair

  • Difficult to get data to/from

  • Does not support advanced process control, MPC, fuzzy logic

  • Lack of technical support

I/O Replacement
(HW only)
$1K+ per IOM $400+ per IOM
  • •Unsupported HW

  • Difficult to find spare parts

  • Costly to replace/repair

  • Not well distributed (marshalled)

  • Lacks diagnostics

  • Does not support digital I/O (FFB, DNET)

  • •Lack of technical support

Networks $50K+ $10K+
  • Proprietary (No COTS HW available)

  • Unsupported HW

  • Difficult to find spare parts

  • Costly to replace/repair

  • Difficult to communicate to “open” systems

  • •Lack of technical support

Source: Control Engineering with information from Rockwell Automation

Rockwell Automation has a three-step DSC migration program .

For other news from the RSTechEd meeting in June, see:
Software upgrades: Rockwell CPR 9 to ship in October
Convergence of IT, controls delivers benefits
Re-target your innovations

Mark T. Hoske , Control Engineering editor in chief