Measurement Computing WaveBook rev.3.0 - Manual (Page 64)

3-32 WBK16, WBK Expansion Options, ch03C 6-21-99 WaveBook User’s Manual
Connection
The figure shows the pin numbers of the
DB-9 connector (1 of 8) on WBK16’s
front panel. The strain gage will connect
to these pins, unless the CN-189, DB9
Adapter option is used. The CN-189
option is discussed in the following
sub-section. DB-9 pinout per channel
Note that
not to plugs
connected to the sensor.
pin-number
orientation applies to
connectors on the WBK16
front panel,
WBK16 Signal Input Connection
Quality cable (such as the CA-177 strain-gage cable) can improve performance of the system, especially
with long cable runs. Use cable with an overall shield connected to the DB9 metal shell. Twisted pair cable
with paired leads for signal input, excitation output, and remote sense input is also beneficial. The wires
should be soldered to the DB9 to eliminate noise created by contact resistance variations. The protective
hoods should be installed over the 9-pin connectors during use to avoid draft-induced thermal-electric noise
in the connector solder joints. Molded cables wider than 1.23 inches will not fit WBK16's connector
spacing.
CN-189, DB9 Adapter Option
The CN-189 option consists of two 7-pad jumpers (P3 and P4), a DB9 connector, and a 9-slot screw-
terminal block. The adapter plugs into WBK16’s Signal Input DB9 connector. With use of the terminal
block and appropriate shorting of jumper pads, the user can easily set up the desired bridge configuration.
A table indicating bridge types and the respective CN-189 jumper pad shorts follows shortly. In some
cases, the user may want to install a resistor at location R1. The electrical relation of CN-189 components
is shown in the following schematic.
The CN-189 is intended for convenience and is not shielded. Higher signal quality will be obtained
with the use of shielded cables (such as the CA-177 strain gage cable).
CN-189, DB9 Adapter Option