Connecting Half Bridge I Config with SCXI 1520 and 1314

[rajat]

Hi! I'm using Half Bridge -I Configuration with SCXI 1520 and 1314, but the diagrams in the SCXI-1520 manual are not very comprehensible to me. Three questions:
1) Is it "necessary" to connect SCx terminals?
2) If yes, why is there no lead resistance "RL" shown?
3) Are one end each of two strain gauges to be shorted externally, or wired all the way upto SCXI-1340?

If u can also post a drawing with actual leads and gauges shown, it will be great.

These questions may seem trivial, but I'm just starting with strain measurement so...

Thanks
Rajat

[RIO-Todd]

Rajat,

If you are wanting to perform a shunt calibration on your strain gauges then the SCA terminals will need to be connected. The reason that no lead resistance (RL) is shown is that the resistance of those leads will not be affecting the reading you are taking. Lead resistances only need to be considered when they are part of the wheatstone bridge.

The strain gauges are R3 and R4 in figure 2-3 on page 2-7 of the SCXI-1520 User Manual (linked below). One side of the strain gauges should be connected to each other, then the other side of the strain gauges need to be connected to P+ and P-. Only connections to the right of the 1314 terminal block (in figure 2-3) are connections you will need to make. I hope this helps.

SCXI-1520 User Manual
http://digital.
ni.com/manuals.nsf/webAdvsearch/ED087ED0FDB34CF5862569DC0068992B?OpenDocument

Regards,

Todd D.
Applications Engineer
National Instruments