I haven't used any HART products, but I do know that Siemens have interface cards for their 300 range of PLC's.
The part numbers are:-
6ES7 331-7TB00-0AB0 and 6ES7 332-5TB00-0AB0
The 331 is a SM331 analogue input module, 2 channel and the 332 is a SM332 analogue output module also 2 channel.
Paul
There are 10 types of people in this world....
Those that understand binary and those that don't!