Temperature measurement is probably the most ubiquitous parameter measured globally. We measure the temperature of the air around us, the soil below us, inside boilers powering our homes, in experimental apparatus, and in just about every industrial process. When you really need to measure temperature accurately the resistance thermal device (RTD) is commonly used for its high precision and accuracy. Unlike digital temperature sensors or thermocouples, the RTD can have 2, 3, or 4 wires and can be a bit tricky to interface with.
We’re here to solve that problem for you with a new product! Why did we design and make a totally new instrument instead of buying something off the shelf? Everything we found had something that we needed to work around it seemed like. Either it had the wrong type of outputs, wasn’t as configurable as we wanted, or wasn’t available with months to years of lead time. Our team was tackling two projects that needed to use RTD sensors and decided we would design the ultimate RTD interface for our customers so nobody ever had to deal with this problem again.
4 Channels of Any RTD Wiring Configuration
Our new interface can handle up to 4 RTDs, in any mix of the 2, 3, or 4 wire configurations! All RTDs should be the 100 ohm variety (PT100 is by far the most common RTD on the market), but we can modify a unit for PT1000 RTDs if your application requires them. Why 4 channels? Most of the projects we have encountered need 2-3 channels of temperature measurement (ambient, process inlet, process outlet for example). We wanted to provide one extra channel for the other 10% of the cases out there. Each of the channels is identical and can be independently configured.
The interface reads the RTDs continually and by issuing a simple read command over the USB serial interface the values of each channel are returned. This means you do not need an external analog to digital converter to monitor and log temperatures! This box, a computer, and your sensors can form a complete data collection system! All for the price of less than an analog to digital converter from some of the other offerings on the market.
You already have an analog to digital converter as part of your system and want to read the RTD in a synchronous way with your other instruments? No problem! Each channel has a 0-10 VDC output that is fully configurable. You can get the minimum and maximum output voltage and what temperature they correspond to on a channel by channel basis. This means if your process only ranges from room temperature to the boiling point of water, you can set up that sensor to output 1V at 10 degrees Celsius and 10V at 100 degrees Celsius. This means each bit of your analog to digital converter is optimized for your application of that particular sensor. Need a good analog to digital converter? Checkout a product like the U6 from our friends over at LabJack!
As far as we’re aware there just isn’t anything else out there that allows this much configuration on the analog outputs. This feature really shines in research labs where resolution is often paramount, but the process of interest occurs over a relatively small range of temperatures.
New Removable Terminal Blocks
We’ve all been there – we need to swap out a sensor and the connections go right into a digitizer that’s stuffed behind or under other equipment. You have to stand on your head while wielding a precision screwdriver to remove the wires. Then the wires fly out of the terminal block hitting something else, shorting it out and now your hair looks a bit frizzier than it did that morning.
The team found some excellent pluggable terminal blocks. Now you can wire up the inputs and outputs somewhere easy, like on the workbench, then plug these fully insulated blocks right into the back of the instrument! Need to change a sensor or reroute a wire? It takes seconds and no tools!
Hook Up Guides Right on the Box
While we are really proud of the manual for this interface, we didn’t want to go dig it out everytime we just wanted to hook up another sensor. We have laser marked the hookup diagrams for 2, 3, and 4 wire RTDs, as well as the analog outputs right on the bottom of the instrument enclosure! This makes it easy to flip it over, remind yourself of how to add another sensor and wire it up without ever pulling out your phone or printed manual.
What about the serial commands to configure the instrument you say? (Yes, we heard that.) Like almost every other instrument we make, just type HELP into the serial terminal and a command summary will be displayed for your reference. Need more clarification, formulas, or any other detail? The comprehensive manual has it all in a convenient hyperlinked PDF.
Tested and tested some more
We’re really excited about this product because it is so generally applicable across domains and industries. We’ve had several of these running continuously for months in labs around the country as test units and the results have all been absolutely great. This isn’t something that has not been tested in labs just like yours!
Finally, we even wrote a comprehensive testing suite that exercises every functionality of the firmware to make sure the code not only works, but isn’t broken in the future by any updates. The testing suite also has a bit of a chaos monkey nature in that it tries setting invalid or nonsense parameters to make sure our firmware protects your results from a miskey of information.
If your next project needs RTDs for temperature sensing, consider giving our new 4-Channel RTD interface a try! It is an economical analog and digital output solution to the most common measurement challenge you face! What will you discover with yours?