
Chapter 2
Configuration and Installation
© National Instruments Corporation
2-37
AT-MIO-64F-5 User Manual
skew of 75 nsec between them. The SOURCE signal shown in Figure 2-19 represents any of the
signals applied at the SOURCE inputs, GATE inputs, or internal timebase clocks. See
Appendix E,
AMD Am9513A Data Sheet
, for further details.
Specifications for signals at the GATE input are referenced to the signal at the SOURCE input or
one of the Am9513A internally generated signals. Figure 2-19 shows the GATE signal
referenced to the rising edge of a source signal. The gate must be valid (either high or low) at
least 100 nsec before the rising or falling edge of a source signal for the gate to take effect at that
source edge as shown by t
gsu
and t
gh
in Figure 2-19. Similarly, the gate signal must be held for
at least 10 nsec after the rising or falling edge of a source signal for the gate to take effect at that
source edge. The gate high or low period must be at least 145 nsec in duration. If an internal
timebase clock is used, the gate signal cannot be synchronized with the clock. In this case, gates
applied close to a source edge take effect either on that source edge or on the next one. This
arrangement results in an uncertainty of one source clock period with respect to unsynchronized
gating sources.
Signals generated at the OUT output are referenced to the signal at the SOURCE input or to one
of the Am9513A internally generated clock signals. Figure 2-19 shows the OUT signal
referenced to the rising edge of a source signal. Any OUT signal state changes occur within
300 nsec after the source signal rising or falling edge.
Field Wiring Considerations
Accuracy of measurements made with the AT-MIO-64F-5 can be seriously affected by
environmental noise if proper considerations are not taken into account when running signal
wires between signal sources and the AT-MIO-64F-5 board. The following recommendations
apply mainly to analog input signal routing to the AT-MIO-64F-5 board, although they are
applicable for signal routing in general.
You can minimize noise pickup and maximize measurement accuracy by doing the following:
¥
Use differential analog input connections to reject common-mode noise.
¥
Use individually shielded, twisted-pair wires to connect analog input signals to the
AT-MIO-64F-5. With this type of wire, the signals attached to the CH+ and CH- inputs are
twisted together and then covered with a shield. This shield is then connected only at one
point to the signal source ground. This kind of connection is required for signals traveling
through areas with large magnetic fields or high electromagnetic interference.
¥
Route signals to the AT-MIO-64F-5 carefully. Keep cabling away from noise sources. The
most common noise source in a PC data acquisition system is the video monitor. Separate
the monitor from the analog signals as much as possible.
The following recommendations apply for all signal connections to the AT-MIO-64F-5:
¥
Separate AT-MIO-64F-5 signal lines from high-current or high-voltage lines. These lines are
capable of inducing currents in or voltages on the AT-MIO-64F-5 signal lines if they run in
parallel paths at a close distance. Reduce the magnetic coupling between lines by separating
them by a reasonable distance if they run in parallel, or by running the lines at right angles to
each other.
Содержание AT-MIO-64F-5
Страница 13: ......
Страница 16: ......
Страница 200: ......
Страница 201: ......
Страница 202: ......
Страница 203: ......
Страница 204: ......
Страница 205: ......
Страница 206: ......
Страница 207: ......
Страница 208: ......
Страница 209: ......
Страница 210: ......
Страница 211: ......
Страница 212: ......
Страница 213: ......
Страница 214: ......
Страница 215: ......
Страница 216: ......
Страница 217: ......
Страница 218: ......
Страница 219: ......
Страница 220: ......
Страница 221: ......
Страница 222: ......
Страница 223: ......
Страница 224: ......
Страница 225: ......
Страница 226: ......
Страница 227: ......
Страница 228: ......
Страница 229: ......
Страница 230: ......
Страница 231: ......
Страница 232: ......
Страница 233: ......
Страница 234: ......
Страница 235: ......
Страница 236: ......
Страница 237: ......
Страница 238: ......