Comparison: ABB TB82PH vs WTW DIQ/S 181

Hey, gang! Here we are again comparing more two products, probably the last analytical transmitters this month. Although the market has a ton we haven’t reviewed, we decided to stick to entry-level multi-parameter devices from different vendors. We may do workups of fancier options in the future, so keep an eye out for those.

A quick story: One of the last projects I did in Brazil before moving to Berlin was a liquid analysis for a plant near a river. For this simple application, I used one of the devices already reviewed here. The system had to constantly monitor the water quality in the river, despite the lack of structure and the distance between the plant and the river.

We used a wireless adapter to power the device in the field and a wireless gateway to send all data to the control system through a Modbus. It was a cool project, simple and cost effective for the customer with its minimal structure.

Back to the comparison!

Our competitors today swing a lot of weight on the market in analytical solutions. ABB has plenty of experience with analysis and a portfolio with a broad range of options. Depending on the country you live in, you may not know the WTW brand, but it has a long path in the automation world as well.

Let’s get to it! On the left, we have the TB82PH, a simple multi-parameter transmitter with everything you need for a simple application. On the right, we have the DIQ/S 181, another initial model in a big portfolio. Let’s find out how these devices might fit in your process!

Grab a venti white chocolate mocha (hey, I like ’em), have a read, and draw your conclusions!

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


Design-wise, the TB82PH is kicking it old-school, and not in a cool retro way. You can get past that if the product delivers an excellent user experience, accurate measurement, and so on, right? But still, to start with a negative impression doesn’t bode well for the rest of the bout.

It has a simple keypad for local setup and a small display with a green backlight. No fancy features, just the necessary functionality you expect from this sort of product.

Unboxing DIQS 181 vs TB82pH
Courtesy of ABB and WTW

The DIQ/S 181 – alphabet soup, anyone? – makes a much better impression out of the box. It looks a lot like a home thermostat, and giving users a familiar design often gets you on their good side.

It has a smaller display than most of its competitors, but the data clearly shows up. Personally, I like the white backlight better than green or orange. No practical reason, I just like it better, so you’re welcome to disagree.

It also offers a keypad for local setup, but you splash into more alphabet soup here. Three of the keys have seemingly random letters on them. What do they do? Hmmm. You can either press them to see what happens or read the manual. Well, go on. Push one and see what happens!


As multi-parameter devices, they should measure more than one variable. If you have more than one channel, you can have multiple sensors on one device, but neither of these can do that. Still, if you have more than one variable to measure, then you can have the same transmitter measuring them, which saves time in setup and verification because they all use the same structure.

The TB82PH can measure pH, oxidation-reduction potential (ORP), and specific ions (pION). However, you have just one input for the sensor, and it only reads analog sensors. If it fits your needs, great! Otherwise, keep looking.

The DIQ/S 181 can measure pH/ORP, conductivity, oxygen, and turbidity. If you need to measure turbidity, you have a very small list to pick from, but having this one on it helps. However, you have the same problem here with input channels. You need to choose one to measure, but you can apply the concept mentioned above.

Housing and approvals

Most of these devices are fairly compact and light. The TB82PH is 144 x 144 x 171 millimeters and 1.9 kilograms without the pipe-mount hardware, and with it, the device is 3.4 kilograms.

For harsh environments, it has an enclosure protection level of IP65 and the most common approvals, such as Factory Mutual (FM), Canadian Standards Association (CSA), and ATREX 100A.

Housing DIQS 181 vs TB82pH
Courtesy of ABB and WTW

On the WTW side, the DIQ/S 181 is around the same size, 144 x 144 x 95.2 millimeters, but lighter, approximately 0.7 kilograms without the accessories.

The enclosure has a protection level IP66, but I couldn’t find the approvals! If it had them, WTW would point them out, right? Drop me a comment below if I’m wrong or the website is just awful!

Power and protocols

The TB82PH uses loop power and has the common protocols – HART, FOUNDATION Fieldbus (FF), and PROFIBUS PA (PB). Of course, you have analog, which you can integrate everywhere. Keeping in mind these devices are the basic options, you can’t expect much, but we can always hope.

Somebody at WTW got a little heavy-handed with the simple concept. First, no loop power, so you need a power cable, although you can use 110/220 volts or 24 volts. Next, no digital protocol, just analog! Big disappointment for me, you know. You have two analog outputs and three relay outputs, but none of those are a protocol.

If you really want a simple device, then you know the best choice! But you need to compare prices and benefits as well.

Fancy features

Not today! Let’s go to the next topic!

Information and documentation

ABB’s website kinda sucks, but it does have two things going for it. One, when you finally find your device page, you can find the right documentation. And two, you can navigate the site fairly easily with your phone. Compared to some vendors, they’re ahead of the game. Sad, isn’t it?

Website comparison TB82pH vs DIQS 181
Courtesy of ABB and WTW

WTW also has a responsive website, with a clearer design than ABB’s. But finding the technical documentation is complicated. The device page only has a brochure. You have to open the Service tab, navigate the Downloads menu, then guess which download will help you most. I found myself downloading the wrong files because the descriptions weren’t clear.


Both devices are entry-level options for these companies. The ABB side has more protocols than WTW, but WTW has the turbidity measurement, a better design, and different output options. Scale out and choose the one that offers you the best cost benefits and most reliable measurement for your application. Then let us know how it goes!

Table of comparison


Table of Comparison TB82pH vs DIQS 181
Courtesy of ABB and WTW


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