Chapter 4
Connecting and Using Accessories and Transducers
4-32
www.ni.com
Connecting to LVDTs and RVDTs
Figures 4-20 and 4-21 show the connections made to a 4-wire and 5-wire
LVDT or RVDT using the SCXI-1540 with the SCXI-1315 terminal block.
Figure 4-20 shows that you can connect a device with six wires using only
four wires. In general, the 5-wire connection is insensitive to phase shift in
the transducer and wiring, but subject to interference from common-mode
voltages in the cable such as AC hum picked up from power lines. It is
therefore advisable to use the 4-wire connection except in cases where a
large phase shift in the return signal is suspected. Causes for a large phase
shift might be the use of an operating frequency other than that specified by
the sensor manufacturer or a cable run >100 m.
Figure 4-20.
4-Wire Connection
Figure 4-21.
5-Wire Connection
Brown
Yellow
Red
Blue
Green
Black
CH+
CH–
SYNC
GND
EX+
EX–
Brown
Yellow
Red
Blue
Green
Black
CH+
CH–
SYNC
GND
EX+
EX–
