Here’s the code:

<form>Water temp deg C:
<input name="temp_degc" type="text" />
Uptime hours:
<input name="uptime_hours" type="text" /></form>

See f.ex. https://www.w3schools.com/html/html_form_input_types.asp

See html “input” field “update” from my home machine (or similar)? on the WordPress.org forum