I have a small furnace that heats a sample of my product, a cylinder measuring 20mm x 100mm. As it is heated, there is thermal expansion, and I at this moment read (using my eyes) a micrometer dial gauge and type into my app the value read in hundredths of a millimeter. My source code uses quartz to draw a PDF graph that represents this thermal expansion. I would like to enhance my set up by getting my app to collect the linear displacement from my dilatometer furnace. One possibility I have been trying to implement is to have my app collect DC millivolts from an instrument, like a voltmeter reading the output of an LVDT (Linear Variable Differential Transformer), but the model I have requires MODBUS-RTU protocol, which is not well implemented by Mac OS X developers. It requires an USB-Serial converter, which complicates things and makes it more unreliable. At this moment, I have to sit next to my furnace and type into my app the temperature and linear displacement for 3 hours. I would like to read some comments and suggestions from you or an Apple Engineer and how this could be achieved. Here is a video of my dilatometer furnace: https://www.correiofacil.com/video/IMG_8888.MOV Here is a PDF I generated using my APP: https://www.correiofacil.com/PDF/117.pdf Here is a video showing how I type data manually into my app: https://www.correiofacil.com/video/recording2.mov Here is a video that shows my app drawing a graph: https://www.correiofacil.com/video/recording1.mov These 2 images show my attempts to use the app ModBusRtuMaster to collect data from the voltmeter which at this moment fails: https://www.correiofacil.com/PDF/8f9be971dee32a58c36b307dbab3dc2d.png https://www.correiofacil.com/PDF/4ac20c2ea762fd42ed340a7a2b567900.png You will notice that although the instrument is displaying 0.000 volts, the data collected changes at each message I send to the instrument, proving me that Modbus RTU set up is not working. Here is a link to the manual of the DC voltmeter I am using: https://www.correiofacil.com/PDF/manual1.pdf Here is an image of the LVDT I am trying to use: https://www.correiofacil.com/PDF/e0349986512f9273b26b209baa3ba5c7.png Here is the manual for the LVDT: https://www.correiofacil.com/PDF/GGD19.pdf I suspect that there could be a completely different approach to collecting the data and inputting into my app, maybe Bluetooth? Maybe using a Mitutoyo gauge such as? This: https://www.mitutoyo.com/Images/CatalogUS-1003/resources/_pdfs_/US-1003_Catalog_251.pdf And a cable with SPC support like this: https://www.gw-style.com/product-p-942977.html I am very grateful for your comments