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EX1629 Preparation for Use 29
RJ-45 Modular Connector (Shielded)
8-Conductor Twisted-Pair, Overall-Shielded
(Example Half-Bridge Connection)
FIGURE 2-1: CONNECTING STRAIN GAGES
NOTE Unused user connections must be left open.
Color Coding per TIA/EIA-568-B
Pin 1 - Orange/White
Pin 2 - Orange
Pin 3 - Green/White
Pin 4 - Blue
Pin 5 - Blue/White
Pin 6 - Green
Pin 7 - Brown/White
Pin 8 - Brown
Pinout for Upper Connector Row
Excitation Sense
Shield Gnd
Sense
Excitation
R Cal
Sense
-
+
-
-
+
Shield Gnd
6
5
4
2
1
3
8
7
Shield Gnd
Excitation Excitation Sense
R Cal
+
-
-
+
Shield Gnd
321 4 5 6 7 8
SenseSense
Pinout for Lower Connector Row
FIGURE 2-2: INPUT CONNECTOR PIN ASSIGNMENT
Depending on the bridge configuration and cable length employed, the wire gauge (and thus
resistance) of the input connections can be a factor in determining ultimate system performance.
For example, in a full-bridge configuration using excitation remote sense, the measurements are
insensitive to the resistance of all connections. However, in a quarter-bridge configuration, the
resistance of the +Excitation and –Excitation connections can be a significant error source if not
properly compensated. For more details, see Maximizing Measurement Performance in Section 1.
BRIDGE CONFIGURATIONS
Figure 2-3 illustrates how to connect a single strain gage in quarter-bridge configuration. As
explained in Maximizing Measurement Performance in Section 1, the –Sense line should ideally
be connected at the gage, instead of locally at the EX1629 input connector. Moreover, the wire
length and gauge of the connections to Pins 1 and 2 should be matched. Fortunately, this is
typically guaranteed by routing both lines as part of the same cable. For this configuration, the
±Excitation Sense lines are not used and must be left open, as opposed to being grounded or tied
together. Whether the gage will be in tension or compression, the connection is the same.
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