Chapter 2
Theory of Operation
©
National Instruments Corporation
2-9
the DAQ-STC asserts the FIFO retransmit signal, which restores the FIFO
data to its original state.
The channel type field indicates the resource type to be used during
the conversion and controls the multiplexer mode selection switches.
These resources include calibration channels, analog input channels in
differential, referenced single-ended, or nonreferenced single-ended mode,
or a ghost channel. The ghost channel type indicates that a conversion
should occur but that the data should not be stored in the data FIFO. This
type is useful for multirate scanning, which is described later in
this chapter.
The channel number indicates which channel of the specified type will be
used during the conversion, while the bank field indicates which bank of
16 channels is active. This bank field is used on boards that have more than
16 channels. These bits control the input multiplexers.
The programmable gain instrumentation amplifier (PGIA) serves two
purposes on the PCI E Series boards. The PGIA applies gain to the input
signal, amplifying an analog input signal before sampling and conversion
to increase measurement resolution and accuracy. This gain is determined
by the gain field in the configuration memory. It also provides polarity
selection for the input signal, which is also controlled by the configuration
memory. In unipolar mode, the input range includes only positive voltages.
In bipolar mode, the input signal may also be a negative voltage. The
PGIA provides gains shown in Table 2-1.
Table 2-1.
PGIA Gain Set Verses Board
Gain
PCI-MIO-16E-1
PCI-MIO-16E-4
PCI-6071E
PCI-6052E
PCI-MIO-16XE-50
PCI-MIO-16XE-50
PCI-6031E
PCI-6032E
PCI-6033E
PCI-6023E
PCI-6024E
PCI-6025E
0.5
✓
—
—
✓
1
✓
✓
✓
✓
2
✓
✓
✓
—
5
✓
—
✓
—
10
✓
✓
✓
✓
20
✓
—
✓
—