Hi Murali
1.) I asume that you're not using NI-DAQmx 7.0.x because I looked into the 1520 example for NI-DAQ 7.0 and there you've the option to select all bridge configuration types. If you're VI is not doing so, then recreate the input control.
2.) The formulas are the same, but the HW setup is different. The QTR Bridge 2 has One active strain-gauge element and one passive, temperature-sensing quarter-bridge element (dummy gauge). This is used for temperature compensation. Please review this tutorial for more informations:
http://zone.ni.com/devzone/conceptd.nsf/webmain/C18F65CE920C115086256D720058325B
Regards,
Luca
Regards,
Luca