Wireless pt 2

In part 2 of this Wireless series, Simon debunks the myths relating to employing industrial wireless instrumentation. Sean asks him questions on battery life, update rates, network design, and scalability of wireless solutions. 

Transcript

Sean   00:02 

 Welcome back to Yokogawa Debunks. This is part two of our series about industrial wireless. In our last episode, we discussed the myths of industrial wireless being a new technology, and we touched on the applications of wireless and discussed a little bit about wireless control. There are so many myths surrounding industrial wireless that we invited Simon back again to continue this discussion. Simon, welcome back again to the podcast. 

Simon 00:44 

 Thank you very much for having me back. I'm excited to continue our discussions on this topic of industrial wireless. 

Sean   00:50 

 Now, Simon, to kick us off in part two, we've got another really good myth for you to try and debunk. This one, I think is one of the most common ones that people using or considering using wireless instrumentation have. That being the fact that they rely on batteries for the power. Now, is it true that wireless devices have a short battery lives? And does this not pose a little bit of a problem, you know, having to replace batteries all the time out in the field? Do you think this is fact or fiction? 

Simon 01:19 

 Well, I think battery life is one of the biggest concerns that people come across. And one of the biggest things that all the people have been interested in wireless have always been asking me. But once again, it's one of the myths that we're going to bust today. Now, it has a bit of a truth behind it in terms of our mindset that we've all had bad experiences with battery life. Consider things like your kid's wireless controlled toys and how often do they come to you and complaining all the batteries are flat. 

What about our mobile phones? How often are we in the middle of a call and all of a sudden, the battery runs flat. So, there's justification for us to be worried about battery life when we're thinking about using wireless devices in process measurement and process control. Who wants to operate a plant that suddenly loses its measurements? Nobody wants that. But the concern about battery life was taken as a critical part of the wireless design from the beginning. So wireless devices are designed to have a very low power consumption and give a long battery life. 

Typically, wireless devices will have a low powered state between measurements to save battery power. They'll power themselves down, turn off the displays, wait for their measurement cycle, then power themselves back up, make the measurement, send the data and then go back to a power down cycle. So the battery life of a wireless transmitter is impacted by a number of things. The most significant one is the update rate. Obviously, the faster the update frequency, the more power consumption. 

These days, though, a number of wireless devices are already on the market that can provide you with a battery life of 10 years if you use a 30 second update rate. 

Another impact on the battery life is whether it's in measurement only or acting as a repeater. With ISA100 wireless devices, you can individually configure the role of each wireless transmitter so you don't have to have a device acting as a repeater if you don't need it. Turning that function off lets you save on the battery life. 

So part of ISA100’s battery life gives you the flexibility and gives you a long service life. As I said, some devices these days can last up to 10 years. 

Sean 03:18 

 OK, in 10 years you’ll get it into the realms of fit and forget there. But you mentioned 30 second update rate now, sorry 30 second update rate. Surely that's a little bit of a slow update rate? 

Simon 03:32 

 Yeah, well, let's have a little bit more of a discussion about update rates and battery lives. So, the battery life, as I said, does depend on the measurement cycle and the type of measurement you're making. But if we had to look at something like Yokogawa’s wireless pressure transmitter, as I said at a 30 second update rate, we can get you a 10 year battery life. At this rate, you're getting over twenty thousand measurements per week from the device and it's lasting for ten years. 

But if we pulled that down and instead of 30 seconds looked at, say, a 10 second update rate. We could still get six years out of those batteries. Even if we went down to the fastest update, which we can do on the world's fastest wireless transmitter at half a second, we can still get over half a year out of those batteries. That's pretty impressive when you think of the transmitter pinging out data every point five of the second twenty-four hours a day, up to six months continuous. 

And when you replace the batteries, the cost of replacing batteries is quite low, at around two hundred dollars per device. And if you're getting an update every half a second, it's costing you less than a dollar a day for the batteries. If you've got really critical applications, though, we can even offer a wireless transmitter these days, which uses a dedicated 24-volt DC power supply, meaning you can have wireless output, but you don't need the batteries. 

This gives you flexibility for applications where local power might be available, but you don't want to run output cables all the way back to your control system, hence getting you away from any further battery issues. 

Sean    04:58 

 OK, so let me play devil's advocate here. In the previous episode, we discussed using wireless for control and now we're discussing battery life. So how do you think these two concepts of control and battery life would work together? I mean, can you really trust a wireless instrument in a control room when you know that there's a risk that the battery may run out at some point in time? 

Simon  05:19 

 Well, I'm going to say, yes you can, but you have to be realistic about your expectations. It all depends on the dynamics of your process. You won't be using wireless control on a very fast acting control application. If you have a slow control loop, then that's where wireless starts to become an option. The wireless devices do give you diagnostics about their battery life. So if you monitor this, it can help you out, too. So, with a wireless device, you get two levels of battery alarm, one being battery low and the other being battery critical. 

And as long as you monitor these and set your maintenance operations accordingly, you can change out the batteries before you lose any measurements, so it really depends on the type of application. You're not going to see wireless control on a very fast temperature control loop. But on something simple, like maybe a tank monitoring or something like that, wireless control can be used. 

Sean   06:08 

 All right. But what about scalability and size of the networks? I mean, I've been having trouble at home with my wireless modem, you know, struggling if I've got too many devices connected at one time. But if I try to relate this then to industrial wireless, you know, how many devices typically can an industrial wireless system handle without drop outs and similar issues? 

Yeah, well, industrial networks were designed for the industrial world, so a little bit different than what we use in our homes. So industrial wireless was designed to be fully scalable. So the largest capability gateways that we have available today can handle up to five hundred wireless devices on a single network. This means a large site can have lots of devices continuously working while minimizing the costs and complexity of their gateway systems. With potentially only a couple of gateway needed across the entire large site, It's easy to set up and maintain. 

With a large number of field wireless devices, you need to use a number of access points and an access point can handle up to 100 devices. So we can deploy up to 20 access points across a site bringing up to 500 wireless devices back to a single management station. So, we really can get that scalability that you're looking for in industrial wireless and give you a large number of devices to cover all your different applications. 

Sean    07:28 

Ok, wireless networks are scalable. But, you know, the investment in the infrastructure is going to be significant. I mean, is it true that wireless is really the best for newly built plants, for example, you know, where they can justify the cost of implementing the new infrastructure as part of the overall build? Or do you think it's probably got more of a place in existing operating plans? 

Simon  07:49 

 That's a good question you've raised there. Actually, what I've seen in my experience, it's quite the opposite of what people think. All the wireless installations that I’ve basically been involved in are all for traditional already operating sites. The older plants are often struggling to get new measurements in. They're facing issues trying to optimize, but they've got things on limitation of access to inputs in their control system. They've got the costs of trying to do wiring on an existing operating plant.And it makes it quite difficult so using a traditional wired solution is often very cost-prohibitive to them and stopping them get the measurements that they need. Where wireless is a solution that allows them to get the data in the cost and the time frames that they need. 

So what you see often on new plants is they're typically designed with all the measurement points they need with extra capacity already built in there and often extra capacity in junction boxes. So it takes a bit of time for those new plants to need to deploy wireless, but they will look at wireless as time goes on. But the majority of people now are in existing sites. 

Sean  08:51 

 OK, but I'm going to keep pressing you about this. The cost issues. You mentioned that wireless can save older plants. I understand. Now, get your point there, than for the new measurements in new plants, you know, but wireless transmitters are generally more expensive than wired. And then you've got the gateways, you’ve got the access points to add as well. So it all starts to build up. So do you really get the cost savings in such a case? 

Simon   09:21 

 Well, it is true that wireless devices are more expensive than a traditional wired device, and it is also true that you have that one off cost of the gateway and access point infrastructure. But as I mentioned there, that is a one off cost, once your gateway infrastructure is in, that’s in for the life of the plant. And then it becomes a lot more easy to to add devices on there. So on a traditional plant, what we've seen is that adding a single new wired measurement can be very expensive. 

Some of the customers that we've been speaking to have said that their costs of adding just one single new measurement point can be anywhere between fifteen to twenty five thousand dollars. So when you keep this in mind, you can very quickly get a return on your investment by going with wireless and sometimes even get payback on the very first install. 

Sean  10:08 

 OK, So it shows that there's actually a lot more to the equation than just the cost of the of the cost of the device. But what about distance? We've got processing plants and manufacturing plants of different sizes of different constructions. And, you know, is this generally a problem with wireless devices on some industrial plants? And I mean, what sort of range can they cover? 

Simon  10:30 

 The range of a wireless device really depends on a couple of things. So we'll go through those. Right now, the first is the antenna gain that's being used and the other big one is the line of sight between the devices. So in a typical installation, if you're using a low gain antenna with a nice clear line of sight, it is possible to get somewhere between five to six hundred meters between wireless devices and using a higher gain antenna, which we have available, we can increase that distance up to around one thousand meters between hops. 

Our wireless network design can include things like a star mesh or a hybrid, which is unique to the ISA100 standard. And using a mesh or hybrid allows us to have repeaters which can hop information through. And the Yokogawa Wireless system can handle up to four measurement hops. So we're talking four hops with potentially five or six hundred meters per hop or even one thousand meters per hop. You can see that it gives you flexibility for getting across a very large installation site. 

And another important consideration is that we need to look at that line of sight in terms of the further the distance that you need to travel, the higher you need to mount those antennas to get your best communication. So if you want to do something like 600 meter distance, you want to get the antenna about five meters off the ground and then you can cover that distance around your plant. 

Sean   11:51 

 Now, you mentioned line of sight and pure line of sight. And there is a myth going out there saying that you've got to have pure line of sight for wireless devices. Is this true? 

Simon 12:00 

 No, you don't have to have pure line of sight between the devices. While it is true that the line of sight is important and a good network design is important as well. You need to understand the limitations of the system and what you're trying to achieve. Line of sight is important due to what we call the Fresnel zone, which is used in communications. And if you can keep this zone nice and clear, you get the best wireless communication quality. 

And if you get a good clear line of sight on your plant, I definitely go for it. But there are applications out there which we see customers are looking to do in which they have already been putting in where it is difficult or sometimes impossible to get good line of sight. But with wireless devices, if you don't have good line of sight, you can still use them in congested areas of plant, and they'll still work effectively. The wireless signal can reflect off different structures. So while a device may not be able to see another device, you can still often get a signal through. 

So with a congested area of plant, an important thing to note is that you really going to drop that communication distance so you got lots of metal and piping around and you won't get six hundred meters between your devices. You might bring that down to something like 20 or 30 meters, but you still get those signals through. So it's really important to do a good survey, work out what you're doing and what distances might be achievable. 

Sean   13:18 

 OK, so say that I'm an end user and I'm now convinced that wireless technology is right for my site, but then I go out there and I realize that there's a number of different industrial wireless protocols available. I mean, the two most common for instrumentation, for example, are the ISA100.11a standard and the wirelessHART standard. Can these two be used together? 

Simon  13:44 

 Yes and no to that question. The two protocols are slightly different communication languages. So, while they have some common items in the standards. There are some differences. So based on that, you can't get an ISA100 device to communicate directly to a wirelessHART device. But there are some gateways coming available on the market now which do support both protocols. So you can have both protocols on the one site communicating back to a single gateway, giving you that flexibility that you're not locked into a single supplier or a single protocol. 

Sean   14:16 

OK, thanks. So, In quick summary, what would you say are some of the differences between the two standards? And why did Yokogawa adopt ISA100.11a? 

Simon  14:27 

 A very good question and one we get asked quite often as well. One of the biggest differences is where the standards came from. So the ISA100.11a standard was developed from the ground up as an industrial wireless network, whereas the wirelessHART standard was basically just an extension to an existing wired protocol. So ISA100 was specifically developed for industrial wireless, having a number of advantages. And that's why you chose to go with this protocol. 

In the wirelessHART standard. It's a full mesh network, meaning every device is a measurement device and a repeating device at the same time. Whereas in ISA100 standard, you can individually configure the role of each wireless device, which allows you to run star, mesh, or hybrid topologies, allowing you to turn repeater functions on or off, saving on battery life and giving you the greatest flexibility in the way you design your system. 

There’s differences also in the network size in terms of the ISA100 supports at the moment, the largest network sizes and also differences in the diagnostics that you can get from some of the devices. ISA100 can also support wireless control, which wirelessHART can't do. And ISA100 also allows tunneling functions where we can pull through data from other protocols, like data from existing HART devices or from Modbus devices and send them across the wireless network. So based on all of that, ISA100 was defined as being more future-proof, and because we built that and believe that that's the best standard for customers to go with over a long term, Yokogawa chose to go with that protocol. 

Sean  16:06 

 Do you think there's ongoing developments with the wireless protocols? 

Simon 16:10 

 Not so much in the protocols themselves, but definitely in the types of solutions that are on offer. So Yokogawa is still investing heavily in research and development on wireless solutions. And just the last year, we've already brought out the world's first wireless noise monitoring solution that can allow you to monitor noise levels across your plant, tackling issues on protecting your people, your plant and the local communities. We're also developing other solutions like wireless corrosion monitoring to detect wear in piping systems. So development really does continue within Yokogawa and also development continues in other ISA100 vendors as well. 

Sean  16:46 

 OK, thanks for clearing that up. And and thanks again for your time today, Simon. Once again, you've busted a number of the myths around industrial wireless. However, we still haven't covered them all. And what we're going to do is we're going to push this to a third episode of where we're going to cover the really big issues of security, reliability, and interoperability. So be sure to join us again on the next edition of Yokogawa Debunks. Thank you very much for listening. 

Transcribed by https://otter.ai