NuDAQ ACL-8112 Series, Руководство пользователя

Страница: 47 / 92

Operation Theorem
•
39
5
Operation Theorem
The operation theorem of the functions on ACL-8112 card is described in
this chapter. The functions include the A/D conversion, D/A conversion,
digital I/O and counter / timer. The operation theorem can help you to
understand how to manipulate or to program the ACL-8112.
5.1 A/D Conversion
Before programming the ACL-8112 to perform the A/D conversion, you
should understand the following issues:
Ø
A/D conversion procedure
Ø
A/D trigger mode
Ø
A/D data transfer mode
Ø
Signal Connection
5.1.1 A/D Conversion Procedure
The A/D conversion is starting by a trigger source, then the A/D converter
will start to convert the signal to a digital value. The ACL-8112 provides
three trigger modes, see section 5.1.2.
While A/D conversion, the
DRDY bit in A/D data register is cleared to
indicate the data is not ready. After conversion being completed, the
DRDY bit will return to low(0) level. It means users can read the
converted data from the A/D data registers. Please refer section 4.2 for
the A/D data format.
The A/D data should be transferred into PC's memory for further using.
The ACL-8112 provides three data transfer modes that allow users to
optimize the DAS system. Refer to section 5.1.3 for data transfer modes.