3.2
DMA LEVEL SELECT
DMA level 1 or 3 may be selected. The default level is level 1 (Figure 3-2).
There are other boards that use DMA levels. Some network boards do and
so do some IEEE-488 interface boards. Check to see if you have other
boards in your computer that use DMA channels 1 or 3.
Figure 3-2. DMA Level Select Switch
3.3
1/10 MHz XTAL JUMPER
The 1/10 MHz (1 or 10 MHz) XTAL jumper selects the frequency of the square wave used as a clock by
the A/D pacer circuitry. This pacer circuitry controls the sample timing of the A/D. The output driving the
A/D converter is also available at the CTR 2 output pin on the main connector.
To maintain full compatibility with the original DAS-16, the CIO-DAS1400 required a 1 MHz crystal
oscillator. When MetraByte redesigned the DAS-16 and added the faster 10MHz crystal, a jumper was
provided to maintain compatibility with older software. The CIO-DAS1400 has the jumper because the
DAS-16 has the jumper. For older software, the jumper must be in the 1 MHz position. If you are not
concerned with compatibility with older software, use the 10MHz position.
The CIO-DAS1400 is shipped with the jumper in the 1 MHz position (see Figure 3-3).
Figure 3-3 Clock Select Jumper
3.4
8/16 CHANNEL SELECT
The Analog inputs of the CIO-DAS1400 can be configured for eight differential or 16
single-ended inputs. Use the single-ended input mode if you have more than eight, low-noise
analog inputs to sample. Using the differential input mode allows up to 10 volts of common
mode noise rejection..
The CIO-DAS1400 comes from the factory configured for 16 single-ended inputs and the 8/16
switch is in the position shown in Figure 3-4. Set it for the type (or number) of inputs you
require. On the CIO-DAS1402/16, this switch is located under the metal shield. If you need
access to this switch, this shield may be removed by removing the two screws on the back of
the CIO-DAS1402/16.
Figure 3-4. 8/16 Channel Select Switch
3.5
BIPOLAR/UNIPOLAR MODE SELECTION
The Bipolar or Unipolar configuration of the A/D converter is set by a switch. This switch is
shown in Figure 3-5.. The switch controls all A/D channels. Although you cannot mix bipolar
and unipolar channels, you can measure a unipolar input in the bipolar mode. (e.g., you can
monitor a 0 to 5V input with a ±5 V channel). On the CIO-DAS1402/16, this switch is located
under the metal shield. If you need access to this switch, this shield may be removed by
removing the two screws on the back of the CIO-DAS1402/16.
Figure 3-5. Bipolar/Unipolar Select Switch
Input amplifier gain is controlled by a software-programmed register located at BASE + B hex (11 decimal). Refer to the Register
Architecture section for details on this register.
-2-
CL
K SEL
1
10
Default 1MHz Shown
16/8 CH AN N EL SE LECT S W ITC H
16 C hannel differential-input
m ode show n
16 CHAN
8
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