Six action items for an aging DCS/PLC

Plant and operations managers need to be aware that their distributed control systems (DCSs) and programmable logic controllers (PLCs) could be obsolete and they should take appropriate steps to deal with the problem. Six immediate action items for an aging system are highlighted.

By Jeff Morton, Cross Company November 25, 2016

Plant, operations, facility managers, or C-level executives of a process manufacturing facility likely don’t get deeply involved in the status of a control system and infrastructure. Interaction with the control system may be periodic updates that are delivered by an engineering manager, which is perfectly reasonable. However, it is typically in their best interest for you to be of the opinion that they are doing a great job keeping your plant online and producing, so the updates that you receive may be rosier than they should be. Because of that, managers may not be getting the entire story, especially if you have an aging control system.

Managers may not be hearing that their team is struggling with equipment failures, worn-out cables, obsolete operating systems on their consoles, and especially equipment sourcing. We’ve encountered equipment sourcing situations that definitely should have raised red flags, such as using remanufactured parts websites and even EBay.

Due to the staff’s resourcefulness, the facility hasn’t had any serious downtime yet, but the clock is ticking. Budgets are always a constraint and capital expenditures may be tight, especially for full distributed control system (DCS) or programmable logic controller (PLC) replacements, which are often multi-million dollar investments. That investment, though, is nothing compared to the cost if the production facility went down and could not recover for a week or more?

What’s even more concerning than that is there are many facilities that are unprepared for system failure or obsolescence, which can have catastrophic consequences. Operations, facility, or engineer managers need to begin preparing for migration of your control system from a legacy system to current and supported architectures.

Good information is critical to success. Discuss the situation with the controls team and potentially a trusted systems integrator. In the meantime, there are a few things the staff can do to help to prepare until there is a plan in place and a budget has been approved.

Six immediate action items for an aging DCS/PLC

  1. Backup
  2. Get copies of all software license files
  3. Update system drawings
  4. Check available spare parts
  5. Make a wish list
  6. Develop a functional specification for a migration plan.

Remember the famous words of Ben Franklin, “By failing to prepare, you are preparing to fail.”

1. Backup.

The best method for obtaining a backup is to take an image of the machines, which this can be difficult if the operating system is old. There are several software packages available to perform this task, but get it done and do it soon, regardless of what is chosen.

2. Get copies for all software license files.

Make copies of all license files. It’s not uncommon to run into a situation where the supervisory control and data acquisition (SCADA) or other types of software are  not technically licensed to the end user. The software was still in the integrator or original equipment manufacturer’s (OEM’s) name. Or, even worse, in another customer’s name. Once you have copies, check with the vendor to ensure the licenses are valid. If they are not, make contact with whoever sold the program because that’s another set of problems.

3. Update system drawings.

This includes panel drawings, P&IDs, network layout and/or one-line diagrams (also known as single-line diagrams), etc. This is the most time-consuming task, but it will pay extreme dividends in the long run. If possible, get electronic copies of your panel drawings and have someone (an engineer, a maintenance tech, or intern) go through all of the input/output (I/O) to ensure the drawings are labeled correctly and all of the wires are marked with wire numbers. If there are decommissioned I/Os, then disconnect them and label them as such.

Please take proper precautions in accordance with appropriate regulations. Also, watch for old network cables as they are prone to come loose. This can cause the process to stop or shut down. As much trouble as it may seem, this exercise will help facilitate the crossover drawings during a future upgrade. This will also be greatly appreciated by your maintenance team while they troubleshoot the aging system prior to an upgrade. If there aren’t drawings available, take detailed pictures and create termination drawings. As long as they are accurate, they will suffice.

4. Check available spare parts.

Immediately review available spares and ensure that you have spare parts for all critical components. The problem is that since the system is old, or potentially obsolete, the cost of the parts are greatly elevated. So take into consideration how long the plant will be running on the old system and when you start your migration. A phased-in approach will provide spare parts as each phase is replaced. By migrating in phases, the blows to the budget are lessened.

5. Make a wish list.

Begin developing a list of priority issues that you would change, if you could. Be sure to include operations and maintenance as well. Include specific problems if you know them, such as specific loops running in manual, field shorts or recurring instrument problems, lack of backup power, safety concerns, or process improvements.

An example is to add wireless systems in the plant so operators could stand at a specific piece of equipment and control it using a handheld operator screen or even a tablet. Be creative. Technology is changing and there are a lot of options available to increase productivity and make system maintenance easier. Don’t forget about the control room furniture. If you upgrade to a modern control system, why not spend a little money on the control room to make the operators’ jobs easier.

6. Develop a functional specification for a migration plan.

There are many request for proposals (RFPs) and specs for upgrades that are less than sufficient to quote a job accurately. It doesn’t mean that a qualified integrator cannot quote the project, but the more unknowns and assumptions that a vendor has to take on, the more contingency they have to put in the quote. It then becomes a matter of who guesses best, is willing to take on the most risk, or play the change order game. Regardless of the method, the corporate budget is also at greater risk with a higher number of contingencies.

A well-done functional specification will allow the company to plan the best method with the requirements that are important to your company and specific to the system. The key is that the results are clearly defined and contingency is minimized. As long as the functional specification is followed, the end results will be how you desired it and not how an integrator interpreted the vague RFQ.

A good functional specification will also provide the company with an accurate budget and sample schedule so everyone can plan and budget for the migration properly.

This preparation and planning for system migration does not have to be outsourced if the capability is there in-house. If the project needs to be outsourced, find an integrator that has experience in performing these types of migrations and the preparation that goes along with it.

The functional design specification is a very important and critical part of this entire process. There are many variations and interpretations on this type of document. It’s crucial for that the selected vendor understands what is needed. Just remember, there is a difference in the quality of the end results.

Effective implementation of these steps will provide the company with spares, backups, and the proper licensing to ensure you are prepared for dealing with the existing system. The drawings and wish list will help to prepare for developing a good functional specification, which is the execution process to ensure that you know your end goals and have engineered the roadmap to get there.

These steps prove a little planning can go a long way to help the company properly plan for dealing with obsolescence when it occurs.

Jeff Morton is a sales manager at Cross Company Integrated Systems Group. This article originally appeared on Cross Company’s blog. Cross Company Integrated Systems Group is a CFE Media content partner. Edited by Chris Vavra, production editor, CFE Media,

Cross Company is a CSIA member as of 11/23/2016.

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