Re: 5 Pt100
One issue with Pt100 is, that you have to limit the operating current to a few mA to limit temperature error. This typically is handled by either using an AD with low voltage input or an amplifier. Basically, a Pt100 measurement doesn't need a stable reference, as long as it's identical with the AD reference. A low noise analog supply is usually sufficient.
But accuracy requirements for Pt100 acquisition may be different, also the existing hardware prerequisites.