Hello,

have a look here
http://support.automation.siemens.com/WW/view/de/59753521/0/en

this is a manual only for the BaseUnits of the ET200SP

Hi,

auxiliary terminals has nothing to do with A1 oder A0.

Both, A1 as well as A0 are available as versions with, or without auxiliary terminals.
Both, A1 as well as A0 are available as versions  "white" or "grey" BaseUnit.

An overview can be found in the manual already posted above.

The most significant difference:

A1 has an internal temperature sensor which can be used as reference junction in combination with analog inputs connected thermo couples. This enables you to use "internal reference" for the thermo couple.

A0 does not have this internal temperature sensor.

regards

sancruz