Data Translation DT300 Series, User Manual

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Chapter 6
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Specifying the Gain for One or More Channels
For DT300 Series boards, you can use software to specify the gain for each analog input
channel entry in the analog input channel list.
Note: For analog input channel 16 (the 16 digital I/O lines) in the channel list, specify a gain
of 1 for the channel entry.
A/D Sample Clock Sources
The DT300 Series board provides two clock sources for pacing analog input operations in
continuous mode:
• An internal A/D sample clock that uses the 24-bit A/D Counter on the board
• An external A/D sample clock that you can connect to the screw terminal panel
You use an A/D sample clock to pace the acquisition of each channel in the channel list; this
clock is also called the A/D pacer clock.
Note: If you enter digital I/O channel 16 in the channel list, the A/D sample clock (internal
or external) also paces the acquisition of the 16 digital input lines.
The following subsections describe the internal and external A/D sample clocks in more
detail.
Internal A/D Sample Clock
The internal A/D sample clock uses a 20 MHz time base. Conversions start on the falling edge
of the counter output; the output pulse is active low.
Using software, specify the clock source as internal and the clock frequency at which to pace
the operation. The minimum frequency supported is 1.2 Hz (1.2 Samples/s); the maximum
frequency supported differs depending on the board type, as shown in
Table 7 .
Table 7: Maximum Frequency Supported
Board Type Maximum Frequency
DT301 225 kHz
DT302 225 kHz
DT303 400 kHz