Lately we've received some questions about one of the key concerns in control: controlling something at a specific point in time.
This tip pulls together some resources for control based on time, day, and date.
Topics: Process control, Discrete control, Tips, optonews, PACs, PAC Project, OptoNews 2015-08-26
Do what when:
In last week’s blog we covered how to set the real time clock (RTC) in a PAC Controller with an accurate time server over the Internet using SNTP.Now that our controller knows exactly what time it is, how do we turn on that pump at 6:00 a.m. on the dot?
Like most aspects of programming, there are a few different ways to achieve the same result, so join me in this week’s blog while we look at one way to manage real-time scheduling.
Topics: Energy management, Process control, groov, Internet of Things, Tips, IoT, PACs, PAC Project
Measure the main power grid frequency, he said. It will be fun, he said…. Actually, pretty sure I said something like, “it will be easy”... and I was mostly right, and best of all, it did turn out to be fun!
It seemed like both a reasonable and easy request. The requirements were to measure the mains power grid frequency to a resolution of 0.01 Hertz, and to do it every 125 milliseconds (roughly; it could be a max of 200 milliseconds, but not much longer).
Why? In this case, the chase is better than the catch. It's enough to say the customer had his reasons, and this blog is about the chase.
Topics: Energy management, Process control, groov, Internet of Things, Remote monitoring, Electronics, Tips, IoT, OEM, I/O
Loop the loop.
PID loops are used in a lot of different applications, and for good reason: they help keep our world under control. If you need to control a process temperature or pressure, you probably are going to use a PID loop. But are they always the right solution?
Ultra quick review; a proportional-integral-derivative control loop (or PID controller) compares a setpoint against a measured input value, and depending on the error, changes a control variable (output). It’s all about math. A PID loop is all about running a mathematical formula over and over at a specific rate.The most common example of a PID loop that I often talk about in our monthly training class is the cruise control on a car. The speed of the car is the input, the accelerator is the output and the setpoint is what speed the car is doing the moment the driver presses the “set” button.
PID loops are so useful that sometimes we too quickly decide to use a one in a process when it may not be the best solution to the problem. In this week’s blog we are going to take a look at one instance where use of a PID loop may not be the best tool for the job.Topics: Process control, PLCs, Remote monitoring, Tips, IoT, PACs, I/O
We rely on our smartphones so much now. It's hard to remember when I couldn't instantly:
So seriously, why would I want that convenience to stop with my personal life?
What I'd like is to also see status and data from equipment and systems I'm responsible for, and especially to be notified if something's out of line.
Topics: Energy management, Process control, Discrete control, groov, Internet of Things, Remote monitoring, optonews, OptoNews 2015-07-15
Star Struck:
From a young age I have been looking up at night. Not sure exactly when I fell in love with astronomy, but I can recall looking up at the stars every chance I got as a kid.
I have ebbed and flowed with the amount of time and equipment I have had to spend on the hobby. In Australia I had a fully enclosed fiberglass domed observatory, which I chose to not ship over when my family moved to The States, but the desire to look up has not gone away.
Only the constellations at the horizon can be seen in both hemispheres, and even those look upside down compared to what I used to see. So I wanted to get something up and running fast here that would allow me some time to get my bearings in the sky and to share my new stars with my mates back in Australia via my personal website.
In this week's blog, I would like to share what astronomy tools I currently have set up, thanks to some Opto 22 hardware and groov.
Topics: Videos, Process control, Discrete control, groov, Internet of Things, Remote monitoring, Electronics, Tips, IoT, PACs
What's on your MicroLogix™ PLC that you'd like to monitor or control from a mobile device?
Machine status? Temperatures and pressures? Valves and pumps?
Whatever it is, you can see it and do it now with a groov mobile operator interface.
In our latest groov Workshop video you'll watch Opto 22's Director of Training, Mary St. John, build and use a simple interface for a MicroLogix PLC that's communicating as a Modbus/TCP slave. You'll learn how to:
Topics: Videos, Process control, Discrete control, groov, PLCs, Remote monitoring, optonews, Integrators, OptoNews 2015-07-01
Accuracy and resolution both appear in specifications for our SNAP analog modules. But what do they mean, exactly?
Let's start with accuracy, which is pretty easy to understand. Accuracy is how close a measured value is to reality, to the true quantity of what is being measured.
Topics: Process control, Tips, optonews, OptoNews 2015-07-01
Layers of security:
I wish there were, but there just isn’t.... There is no one device, hardware, or software that is the single defense for all known and future network attack vectors—including the one critical weakness: humans. You know, some thing or device that you could simply put at your network's front door and have it reject all the bad guys, but allow the friendlies in without question. Secure and easy is still a wish.
The solution then really comes down to layers. Adding layers that each will take a lot of time and a lot of effort to peel back, so much so that most attackers simply give up and move on.
The past few blog posts have talked about some of those layers, so let's now put it all together and see just how we might go about building a very robust mobile-accessible industrial automation network.
Topics: Process control, Discrete control, groov, Internet of Things, PLCs, Remote monitoring, Electronics, Tips, IoT, Machine builder, PACs, OEM, Integrators, Networking
Would you like to view critical plant status from anywhere on the Internet?
Are you worried that if you connect your automation network to your company’s IT network (which is likely connected to the Internet), the wrong people could access your control system? Or that traffic like YouTube might impact your automation network throughput?
There are a lot of advantages and only a few disadvantages to segmenting your IT (Information Technology) network from your OT (Operational Technology, in other words your controls) networks. While there are a few different ways to segment networks, in this blog we are going to look at separating them using one of two Opto 22 products: SNAP PAC Controllers and groov.
Topics: Process control, groov, Internet of Things, Electronics, IoT, Machine builder, PACs, Networking