On August 27th, 2019, SpaceX launched its Starhopper rocket prototype 150 meters above the plains of south Texas and then landed it gently on an adjacent landing pad. (You can read more and watch the video here) This was another successful step forward for SpaceX founder Elon Musk’s goal of reaching Mars. However, August 27th wasn’t the original launch date; August 26th was. A technical failure caused the rocket to abort mission just before takeoff, leaving SpaceX scrambling to review mission data and see what went wrong. In this case, a simple ignition wiring issue was the culprit. Imagine a world where SpaceX didn’t have that data though. The launch fails, and all they know is that the rockets never ignited like they should have. It would sound crazy for them to just make some adjustments “that could be it”, cross their fingers, and hit launch again, right? Of course!
Unfortunately, too many times we see control systems managed this way. Control systems create a massive amount of data during operation, but few owners capture that information, much less convert it into actionable insights that influences decision-making. So how do you capture it? Let’s look at control system historians. What are they? How do they differ from a standard HMI (operator interface)? How can they help you make decisions and save money?
What is a historian?
Basically, a historian is a recorder that logs specific data values at set intervals for the purpose of summary and review. In a well-planned control system, your data will be gathered by your controller, organized into tags, and then passed to your historian. However, that passing of data is limited and intentional. In other words, while your controller can manage thousands of data tags, your historian will have a limited number of tags for which it can store data, so you’ll need to choose them wisely. One important point to note is that your controller should pass data to your historian and your HMI control interface separately; they can’t be placed in a single line of data.
Why is this? It really comes down to the fundamental purpose for each. A historian is designed to store large datasets. Once the data is in your historian, it can be reviewed and summarized to help you see machine trends, predict maintenance schedules, increase output, and more. This data should be reviewed consistently, but it’s rarely viewed in real-time. HMIs, on the other hand, are intended for monitoring and control of your system live, in real-time. Whether on a PC or on the panel itself, HMIs show you current system status, alert you when your system triggers pre-programmed alarms, and give you a graphical interface to adjust setpoints and initiate actions (“Refill Tank”, for example). An easy way to remember this is that on a well-built system, HMIs read and write control system data, while historians read and record that data and translate it to insightful reports about system trends.
How do historians make you money?
So, why does all of that historian data matter? Good question. In the case of SpaceX’s failed launch, they were able to use it to see what went wrong. Machine fault identification is certainly one function of this data. Don’t waste a downtime! Historian data allows you to see the changing variables leading up to and during a downtime incident so you can identify causes and prevent those issues in the future. HMI pre-programmed alarming was mentioned above. Historian data can let you know that if your machine reaches a certain temperature for a sustained time, it will trigger a series of events leading to major downtime. Program your HMI alarm to alert you before the downtime event, correct the problem, and your historian data has just saved you substantial lost revenue and repair costs. This data can help you with preventative maintenance. You may learn that your machine loses alignment and faults after X many runtime hours, so you have it tuned before it reaches that fault trigger, again saving downtime and repair. Another use for this historian data is operational efficiency increases. By building a record of outcome, you can experiment and, say, find the setpoint combination that allows you to make the most product while minimizing your electricity usage, saving you money.
These are just a few ideas of how this data can be used. Trying to make operational decisions and diagnose problems based on only on live data vs. historian data is the difference in using a narrow picture vs. a 360° video to identify a landmark. The picture gives you a single snapshot, but video gives context. Without context, there’ll be a healthy amount of guessing and conjecture, and you may end up confidently guessing the wrong place and never realize it.
Without the full context, SpaceX would be launching rockets with decades-old NASA guidelines, conjecture, and some luck; in other words, blindfolded. Instead, they’re well on their way to Mars.
Take the blindfold off. Call us today.
(Featured image source: Elon Musk on Twitter; SpaceX story source: CNET)
