National Instruments DAQ Series, Руководство пользователя

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Chapter 3 Connecting Signals
© National Instruments Corporation 3-13 DAQCard-700 User Manual
The common-mode voltage is measured with respect to the DAQCard-700
ground and can be calculated by the following formula:
V
cm-actual
= (V
+
in
+ V
–
in
)/2
where V
+
in
is the signal at the positive input of the instrumentation
amplifier and V
–
in
is the signal at the negative input of the instrumentation
amplifier.
If the input signal common-mode range exceeds the maximum value
(computed above) with respect to the DAQCard-700 ground, limit the
amount of floating that occurs between the signal ground and the
DAQCard-700 ground.
Connecting Digital I/O Signals
Pins 22 through 37 of the I/O connector are DIO signal pins. Pins 22
through 29 are digital input pins. Pins 30 through 37 are digital output pins.
Pins 19 and 50 are digital ground pins.
Refer to Appendix A, Specifications , for more information about the
specifications and ratings for the DIO lines.
Figure 3-6 shows an example of connections to the digital input and output
ports. Digital input applications include receiving TTL signals and sensing
external device states such as the switch in Figure 3-6. Digital output
applications include sending TTL signals and driving external devices,
such as the LED shown in Figure 3-6.