Theory of Operation
Chapter 4
DAQCard-500 User Manual
4-2
© National Instruments Corporation
The following are the major components making up the DAQCard-500:
•
PCMCIA I/O channel interface circuitry
•
Analog input circuitry
•
Digital I/O circuitry
•
Timing I/O circuitry
You can execute data acquisition functions by using the analog input circuitry and some of the
timing I/O circuitry. The internal data and control buses interconnect the components. The
theory of operation for each of these components is explained in the remainder of this chapter.
The theory of operation for the data acquisition circuitry is included with the discussion of the
analog input circuitry.
PCMCIA I/O Channel Interface Circuitry
The PCMCIA I/O channel interface circuitry consists of an address bus, a data bus, interrupt
lines, and several control and support signals. The components making up the DAQCard-500
PCMCIA I/O channel interface circuitry are shown in Figure 4-2.
PC I/O Channel
Address Bus
Timing
Interface
Data
Buffers
Interrupt
Control
Address
Decoder
Control Lines
Data Bus
IRQ
Register Selects
Timing Signals
Internal Data Bus
Interrupt Requests
PCMCIA
I/O Channel
Card
Information
Structure
PCMCIA
Control
Registers
Figure 4-2. PCMCIA I/O Interface Circuitry Block Diagram
