Fix SIEMENS MPI PC Adapter

Hi!!
Need somebody with the knowledge of electronics of the SIEMENS PC Adapter(RS232/MPI).
While extending the MPI cable +24V went to the LTG_A (Data Line) and I think the line buffer was blown up???

Anybody know wheteher these adapters can be repaired at reasonable price!!
Any idea which IC is the Data Line A input interfaced to????
Now the power LED lights up but there is no communication between the PC and the CPU!!

Forget about repairing the PC/MPI adapter.
Its not so expensive, around 250 EURO.
There is a new version thats connects via the USB port in stead of the serial port. But you must check that you have recent versions of STEP7 in order to use it.