Hello Will;

Did you really meana Sitrans LU250 HART, or did you mean a Sitrans LU250 Profibus-PA?

If you want to use HART communications, you would need the following HART input module, and it can only be mounted on a Profibus-DP slave station (ET 200M):

If you do intend to use Profibus-PA in your project, please look at the recent thread giving abasic overview on connecting PA instruments to a DP-master:

Topologi

In the meantime you could look at the manuals for both types of intrument, so you can see the differences between the two (as far as communications with the PLC):

SITRANS LR250 (HART) - Operating Instructions

SITRANS LR250 (PROFIBUS PA) - Instruction Manual

Hope this helps,

Daniel Chartier