Keithley KPCI-3110, Руководство пользователя

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KPCI-3110 and KPCI-3116 User’s Manual Functional Description 2-17
Output filters
On the KPCI-3116 board only, each DAC supports a software-selectable, single-pole, filter of
20kHz. Specifying a 20kHz filter is useful if you want to smooth the output values of the DAC.
On power-up or reset, no filter is used. Refer to DriverLINX manuals for more information on
filters.
Output ranges and gains
Each DAC on the KPCI-3110 or KPCI-3116 board can output bipolar analog output signals in
the range of ±10V.
In DriverLINX software, specify a gain of -1 for bipolar analog output operations. This sets both
range and gain.
If you are using an analog output channel list, the subsystem defaults to a gain of 1 for each
channel; therefore, you do not have to specify the gain.
D/A output clock sources
KPCI-3110 and KPCI-3116 boards provide two clock sources for pacing the output of each
channel in the analog output channel-gain list:
• An internal D/A output clock that uses the 24-bit D/A Counter on the board.
•
An external D/A output clock that you can connect to the screw terminal panel
The following subsections describe the internal and external D/A output clocks in more detail.
Internal D/A output clock
The internal D/A output clock uses a 20MHz time base. Conversions start on the falling edge of
the counter output; the output pulse is active low.
Through software, specify the clock source as internal and the clock frequency at which to pace
the analog output operation. The minimum frequency supported is 1.2Hz (1.2 Samples/s). For
KPCI-3110 boards, the maximum frequency supported is 500kHz (500 kSamples/s). For KPCI-
3116 boards, the maximum frequency supported is 200kHz (200 kSamples/s). See
page 2-19 for
more information on these conversion modes.
External D/A output clock
The external D/A output clock is useful when you want to pace analog output operations at rates
not available with the internal D/A output clock, if you want to pace at uneven intervals, or if
you want to start pacing when an external event occurs.
Connect an external D/A output clock to screw terminal 74 on the STP-3110 screw terminal
panel (pin 9 on connector J2). Conversions start on the falling edge of the external D/A output
clock signal.
Using software, specify the clock source as external. For KPCI-3110 and KPCI-3116 boards, the
clock frequency is always equal to the frequency of the external D/A output clock input signal
that you connect to the board through the screw terminal panel.