National Instruments Corporation SC-207 Series, Руководство пользователя

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Chapter 2 SC-2070 Board
© National Instruments Corporation 2-3 SC-207X Series User Manual
To
Input
Multiplexer
AIGND
+ Channel
- Channel
+5 V
A
B
C D
+
-
E
F
G Factory-Installed
Jumpers
Figure 2-2. Onboard Equivalent Circuit
The components are numbered differently for each channel. Table 2-1 lists the components in each
channel and their correspondence to the circuit shown in Figure 2-2.
Table 2-1. Component Positions in Each Channel
Channel (Position in Figure 2-2)
Differential Single-Channel A B C D E F G
0 (0,8) R2 R1 R5 R4 R3 R6 C2
1 (1,9) R8 R7 R11 R10 R9 R12 C3
2 (2,10) R14 R13 R17 R16 R15 R18 C4
3 (3,11) R20 R19 R23 R22 R21 R24 C5
4 (4,12) R26 R25 R29 R28 R27 R30 C6
5 (5,13) R32 R31 R35 R34 R33 R36 C7
6 (6,14) R38 R37 R41 R40 R39 R42 C8
7 (7,15) R44 R43 R47 R46 R45 R48 C9
When the board is shipped, jumpers are inserted in the E and F positions of the input network (see
Figure 2-2). These jumpers can be easily removed to build analog input signal conditioning circuits.
Several applications showing the use of these open component positions are discussed in Applications
later in this chapter.
Temperature Sensor
The SC-2070 board is equipped with an onboard temperature sensor for use with thermocouple cold-
junction compensation. This sensor, a National Semiconductor LM-35CZ, generates a voltage output
of 10 mV/
°
C, with an accuracy of
±
1
°
C. The sensor is jumper-selected on differential input channel
0. The MIO-16 board can be configured for either differential or single-ended inputs if this
temperature sensor is used. Jumper W1 is used to select either the temperature sensor or the external
screw terminals as the input source for differential channel 0. If the temperature sensor is chosen, any
signal conditioning that has been installed on channel 0 is ignored and has no effect. Figure 2-3 shows
the positions for jumper W1.