Xycom XVME-500, Руководство пользователя

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XVME-500/590 Manual
February, 1988
3.4.1
A/D Conversion Modes
The A/D conversion process can operate in any one of four possible conversion
modes. They are:
M O D E DEFINITION
0
Single Channel Conversion: Repeated A/D conversions are performed
on a specified channel.
1
Sequential Channel Conversion: Channels are converted in sequence
beginning with a specified channel.
2
Random Channel Conversion: A single A/D conversion is performed
on the selected channel.
3
Externally Triggered Conversion: A selected channel will be
converted only when a positive trigger signal (referenced to
logic ground is received on Pin-50 (ground reference on Pin-49)
of connector JKI.
Four conditions may cause a conversion to be initiated. These conditions are:
1)
Writing to the channel/gain register in random channel mode, with data
bit 5 at a logic ‘0’
2) Reading the low byte from the ADC while in the single or sequential
channel mode
3)
Execution of the convert command
4)
Initiating an external trigger
A jumper-selectable settling time is provided for the two instrumentation amplifiers
and for the amount of time (they) take to settle. Settling times of I0uSec, 16uSec,
24uSec and 80uSec are available.
NOTE
If the programmable gain amp is used, 10uSec
settling is all that needs to be jumpered. The fixed-
gain amp, however, requires a settling time of 24uSec
for gains of 1 to 100, and 80uSec for a gain of more
than 100.
3-15
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