Upgrading PLC-5 automation systems has been on the food and beverage industry’s radar for quite some time now.
In fact, when I began working at Stellar 12 years ago, people were buzzing about Rockwell Automation moving the processor into retirement (“Silver Series” status). However, the PLC-5 1771 was such a widely popular system, Rockwell held back on pulling the trigger until recently. In August 2012, Rockwell revealed it would no longer support the PLC-5 processor anymore, including engineering replacement parts — big news, considering more than 80 percent of the marketplace owned these systems.
Why you must migrate your PLC-5
Upgrading involves moving from a PLC-5 to a 1756 ControlLogix®.
If you don’t upgrade your PLC-5 processor, you’re constrained by an outdated, limited platform that isn’t supported and is no longer manufactured. This means spare parts are also no longer made for the control system.
A decade ago, people knew its retirement was only a matter of time: Silver Series status was in PLC-5’s future. However, because these systems are very reliable, people tend to put off upgrading them — an if-it-isn’t-broke-don’t-fix-it mentality.
Now, this Silver Series status has been applied to a growing number (now the majority) of the PLC-5 and 1771 I/O products. For those products, spare parts may currently be available, but this could change at any time. Silver Series really is a measure Rockwell has taken to clearly communicate that NOW is the time to upgrade. If you wait, and you don’t have the spare parts, they may be no longer available, and then you will be searching eBay for used parts.
If your control system goes down, you lose production time, product quality and/or money from either renting equipment or having to pay personnel to perform the control system’s tasks manually.
Unfortunately, many PLC-5 users have yet to upgrade their control systems. Why? Often, the most common concern I hear from end users is “if it ain’t broke, don’t fix it.” People are hesitant to migrate their control system, especially if there’s nothing wrong with it, per se. Often, they view the PLC-5 upgrade as the giant elephant in the room.
They also believe that the upgrade process is:
- Going to result in significant downtime
These are, of course, myths. In fact, the upgrade can be done effectively and affordably. Plus, turnaround can be quite quick with minimal impact on production. Migrating to current, and better-supported technology not only ensures you have access to critical spare parts and other support, but facilitates current and accurate documentation, as well.
Billy Swinson, a colleague and local Rockwell distributor in Jacksonville, Florida, said that concern over documentation often holds PLC-5 users back from upgrading. Due to the 20-plus-year life of the system, plant owners’ documentation isn’t current, so they’re unsure of what has been done to the system over the years since the equipment was installed. As a result, they have old drawings and multiple copies of programs, not knowing what they really have.
However, upgrading your PLC-5 is actually a way to get rid of the clutter, Swinson says. Part of the commissioning process for the upgrade involves going through and matching up existing programs, drawings and documentation. Upgrading kills two birds with one stone, allowing you to see where discrepancies exist so you can ensure all of your documentation is up to date at the end of the upgrade process.
Control system upgrade options
There are a few options you have when upgrading a control system.
Swing arm migration kit
This upgrade option allows you to keep the existing field wiring in place, using an adapter kit to bridge the gap. The swing arm migration kit facilitates connecting wires from the old PLC-5 I/O module terminals directly into the new ControlLogix platform without any rewiring. It’s designed to mount on the same profile holes as the old hardware with the benefit of not needing a drill to complete the process.
Though there is design and engineering work beforehand, the hardware conversion takes about 4 to 6 hours, followed by a recommissioning effort to ensure everything is functioning correctly.
Complete panel replacement
If you’re not making a direct PLC-5 to ControlLogix migration, the swing arm kit isn’t an option for you. The other option involves a complete panel replacement, or building an entirely new back panel, putting all old wires into new terminals.
The pro for this option? Everything is new. You will get a completely updated system without having to redo the field wiring (a benefit of both upgrade approaches). This process can be completed with any control system, regardless of the existing architecture.
The con, however, is that the hardware installation process for this option is much lengthier, requiring 24 hours per panel.
Commissioning is better with the swing arm migration kit vs. complete panel replacement
A facility must limit its control system’s downtime, requiring it to be back in operation after a set amount of time. By reducing the amount of time required to physically install hardware, the swing arm conversion method leaves more time in that fixed window for checking for correct operations. The result? A more thorough checkout.
On the other hand, when doing the full back panel replacement, 24 hours must go by before the commissioning effort can really begin. Often, it is not possible under those circumstances to complete testing before equipment must be placed back into operation.
Additional tips for migration
At Stellar, we’ve assisted in PLC-5 upgrades from both a reactive and proactive standpoint.
For one food facility, they moved forward with an upgrade because they realized they couldn’t find any support for their control system.
Then, for another facility, their PLC-5 system was running just fine; however, because their plant utilities are critical, they couldn’t simply afford to take the risk of having their processes seize unexpectedly. They planned ahead for downtime around the Fourth of July, ensuring programming, engineering and reviewing was completed ahead of time so the migration only took a matter of hours.
Take a proactive approach for upgrading your controls system, budget for it for your next fiscal year. Look at your calendar and put it on your schedule so you can plan for the necessary (but not substantial) downtime. It’s also important to ensure your upgrades are completed by an integrator with prior success in performing system migrations.
If you’d like to learn more about upgrading your PLC-5 processor, feel free to email me at email@example.com.
Stellar is a fully integrated firm focused on planning, design, pre-construction, construction, refrigeration, mechanical & utility, building envelope, and total operations & maintenance services worldwide. Visit the company's blog at www.stellarfoodforthought.net