Thankyou again. I think it will be a 3 wire PT100.
If the project going to fly, I probably need to keep an eye out for a controller and have a play.
Might be worth a "wanted" post
Hmm. I would really like to fiddle with one before purchase.
Might download the app and see what it will do without connection.
Are there any good tech details / PDFs etc, the instructions are a bit basic?