Comparison: OleumTech vs Rosemount 248

Let’s check more two field devices and how they can support you in a new application! In this comparison, we have two wireless temperature transmitters with different protocols and very different approaches.

On the right, the crew of Emerson is at Visaya again, this time with the Rosemount 248, a compact device with two versions. We’ll talk about the compact version with the internal wireless antenna today. On the left, the gang from OleumTech appears for the first time here! The title of this post may look like we’re throwing the entire company at the Rosemount 248, but not so. OT has a different approach to portfolios, so we’re sort of reviewing an entire line instead of one model. Make sense? If so, then great! If not, then keep reading. I’ll explain later.

Are you ready for another comparison? Let’s check the features and see how you can fit these devices in your process.

Disclaimer: This product review examines only features, not performance. If you’ve used this device, feel free to share your experience in the comments.


The first impression you get from an OleumTech temperature transmitter is that of a robust device with a – shall we say classic? – design. The OT developers focused on polishing the features rather than the device itself.

This company has boldly committed to wireless communication, and all devices have wireless connections only. We applaud this innovative approach, as wireless continues to expand in our industry. We also applaud the impressive signal range of OT devices.

You can choose a local display, where four buttons let you set up the device and navigate the menu. The buttons have function numbers, and on the display, you can see the function for each. Sadly, OT doesn’t have much public information on this part. I’ll tell you more about that later too.

Speaking of which, let’s address our first postponed point. OleumTech has 10 models of temperature device. If you want a resistance temperature detector (RTD) input with a display, then you buy the RT1. But if you want a third-party sensor and display, you have to switch to the RT2. I don’t get it. Other companies offer one transmitter for many inputs, with/without display, and so on. That seems like a good idea, so why this? I’d love to hear from an OT rep!

Unboxing Rosemount 248 vs OleumTech
Courtesy of OleumTech and Emerson Automation Solutions

The Rosemount 248 has a compact, innovative design with an integrated antenna and optional display. I like this new approach. You can find two versions of the 248, one with the traditional external antenna and aluminum housing, and the other with the polymer housing and internal antenna. We’ll stick to the second version here.

On the local display, you can see the process variables, diagnostics, network information, and battery status. No buttons, though. You have to use a HART handheld to set up. You can make changes remotely afterward.

Measuring input

Let’s begin from the Emerson side. You can connect only one temperature sensor to the Rosemount 248. Yes, it’s a budget model, but that limits you a lot. However, the Rosemount device can read RTDs, thermocouples, resistance, and millivolts. The resistance and millivolts mean you can integrate different sensors to use these outputs. Nothing new there; most temp devices on the market have this range.

Back on the OleumTech side, we have a complicated situation because of the model thing. First, OT’s temp line can read RTDs and type-K thermocouples. Yes, just type-K. Beyond that, I never found clear information saying anything about resistance or millivolts.

Now, if you want to read an RTD sensor, then you have the RT1, RT2, RTD, and RTM options. The RT1 has an integrated sensor and a display, the RTD has no display, the RT2 reads third-party sensors and has a display, and the RTM does the same with no display. Did you get all that? Because there’s more. The thermocouple versions reflect a similar pattern. The TC1 has a display and supports third-party sensors, and the TC has an external sensor but no display. Simple, right?

Field protocol and output

Both devices have wireless as the only communication option, but you’ll still find differences between Emerson and OleumTech. We could have philosophical conversations about open and proprietary protocols, but we’ll stick those in the box with the Android/iOS and Mac/Windows chats. Note: I defend open protocol, but I love my iPhone. Yup, totally contradictory! Humans do that sometimes.

Anyway, the Rosemount 248 supports the (open) WirelessHART protocol, so you can have third-party devices on the same network. The compact version of the 248 has an integrated antenna, so you can’t extend its range with a high-gain antenna.

Application Rosemount 248 vs OleumTech
Courtesy of OleumTech and Emerson Automation Solutions

The OleumTech transmitters use the OTC sensor network, where you can have all OleumTech devices in a star topology, peer to peer, or point to multipoint. You can choose a device with an antenna of 2.4 gigahertz (GHz) or 900 megahertz (MHz). I don’t like proprietary field networks, but maybe a small or fast application can justify it.

Performance, battery, and approvals

The performance for either device depends on the sensor you have. You can find this information on the datasheet, showing the accuracy per sensor.

OleumTech provides some general info. For instance, the version that reads RTDs has an accuracy of +-0.1 degree Celsius. By the way, if you buy a device with the RTD already included, you can pick a sensor between 2 to 18 inches and get a temperature range from -55 to 260 degrees Celsius.

Emerson also gives a list of sensors and their accuracy on the datasheet. For example, the Pt 50 with a measurement range from -200 to 550 degree Celsius has a digital accuracy of +-0.9 degrees Celsius.

Now battery life, an important factor with wireless transmitters! OT offers estimated performances depending on the device, antenna, and other factors, but it gives the max as seven years. If you have a 2.4 GHz antenna at 10 milliwatts and an update rate of 10 seconds, you can get a full year. Moreover, the device is intrinsically safe, and you have a list of certifications for hazardous and harsh environments.

The Rosemount 248 battery can reach 10 years! Optimally speaking, of course. If you want to estimate your battery life, check out Emerson’s online tool, the Power Module Life Estimator. It’s easy to use and should give you a fair idea of battery life in your process. If you set a 4-second update rate in a well-formed network with an ambient temperature of 30 degrees Celsius, then you could get 2.8 years.

Fancy features

Both devices provide digital communication, easy integration, and diagnostics, but not much else. Next topic, please.

Information and documentation

Yes, we love the Emerson website – a good, responsive design you can explore with your phone or tablet! It also offers blogs, whitepapers, and a community where you can learn more about devices and talk to experts.

Website Rosemount 248 vs OleumTech
Courtesy of OleumTech and Emerson Automation Solutions

OleumTech’s website is simple but quite good – surprising in this industry. I liked  clarity of the device icons. You can even use your phone or tablet to navigate it! On the down side, when I tried to download files to learn more about the devices, the site asked me to fill out a form for access. Really? After you comply, you have to wait for approval before you can log in and check things out. If you want to protect certain whitepapers or presentations I get it, but to download necessary files? Nah.


On one side, you have a proprietary protocol and different device concept. You may like that. On the other, you have an open protocol and one device for most applications. What do you prefer? Remember, you need to review local support, accuracy, interoperability, and price before deciding. Not that easy, huh?

Table of comparison

Table of Comparison Rosemount 248 vs OleumTech
Courtesy of OleumTech and Emerson Automation Solutions


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