Product Review: Endress+Hauser RMA42 universal transmitter

Today, let’s talk about a device built for a broad range of applications, the RMA42 from Endress+Hauser. Usually, we review devices dedicated to a certain application, with a few variations. But this universal transmitter can receive a bunch of different sensors and outputs. It also has good features and can act as a control unit.

Let’s dive into its specs and see what its pros and cons look like. Stick around to learn about the RMA42!

Disclaimer: This product review examines only features, not performance. If you’ve used this device, feel free to share your experience in the comments. This content serves the purpose of providing information if you want a new device.

Whatcha got there?

The RMA42 measures out at 45 by 115 by 118 mm (1.77″ x 4.53″ x 4.65″) and installs on a DIN rail. This device also offers a local interface, so you can set up easily, even if you haven’t used an Endress+Hauser interface before. Or you can connect a computer to it with its PC interface connection port and use FieldCare or DeviceCare to set up. These choices let you find the best way for you to configure it smoothly.

Image for image for Endress+Hauser RMA42 universal transmitter
Image courtesy of Endress+Hauser

It also shows all the measurement and control data on its 5-digit, 7-segment, backlit LCD display. Plus it has a bar graph, tag unit, and a failure alert. You can see alarms and error messages with the LED and the relay status. It also has instructions printed on the side for connecting the sensor and output, a big help, if you don’t like juggling the manual in the field.


What can it do?

The RMA42 has up to two inputs with a handful of configuration choices – one universal input and one analog output, two universal inputs, or two analog outputs. Check your needs to see which setup will suit you better.

The device can read thermocouples, resistance, current, and voltage, making all kinds of field sensors possible. It also has current and voltage output, two relays, and an open collector.

It can power up on 20 to 250 volts of alternating or direct current, so finding a power supply will be easy. But do you need a power supply for the sensors connected to the RMA42? Nope. It has a 24-volt intrinsically safe loop for your field devices. Sounds good, right?

For certifications, it has FM, CSA, UL, and more. On top of that, it has a safety integrity level of 2 (SIL 2). If you want to know more about SIL, then check out this #WishIknew.

Why should I care?

For starters, you can connect two sensors to this transmitter to monitor your process. It can also control part of your process and integrate its data into your system.

Image for image for Endress+Hauser RMA42 universal transmitter
Image courtesy of Endress+Hauser

The RMA42 has a long list of software functions, expanding its possibilities. It can do calculations such as sums, differences, means, and linearization. For the last, it can define up to 32 points to linearize the input.

Want more? Okay. It has limit monitoring and sensor monitoring (NAMUR NE43), not to mention the capacity for measuring differential pressure. Connect two pressure sensors to the unit and voila!


The RMA42 gives you plenty of options for reading data from various field devices. And the control unit feature lets you manage final elements or even set an alarm using its outputs. Last but not least, the software brings a lot of functionality.

Buy RMA42 process transmitter in our online shop

I didn’t find a video for the RMA42 but I found this one:

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