Thanks for your answer.
To the best of my knowledge this is their website: http://hwt.co.za/ however I can't find any mention of the RTU device inside.
I got some data from articles such as this one (see abstract): https://www.mysciencework.com/publication/show/4523ff6713963a0803e814deece75d78
It mentions DNP3 and I saw another speaking about MODBUS, thus I was wondering if these protocols were the only ones implemented on the device or if others were present (e.g.: OPC, probably not OPC-UA since it was in 2000).