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Chapter 3
Signal Connections
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National Instruments Corporation
3-5
Digital I/O Connector Signal Connection Descriptions
Table 3-1 describes each signal connection on the 68-pin VHDCI
connector.
Table 3-1.
I/O Connector Signals
Signal Name
Description
VIDEO0±
VIDEO0± supports RSE connection only. To operate in RSE mode, you must
connect VIDEO0– to DGND. When you use or VIDEO0–, you must
disconnect the BNC connector.
VIDEO<3..1>±
VIDEO<3..1>± allows for a DIFF or RSE connection to video channels
1, 2, and 3. To operate in RSE mode, connect VIDEO<3..1>– to DGND.
PCLKIN±
Use PCLKIN± when the NI 1409 is in external lock mode. In this mode,
PCLKIN represents the A/D sampling clock. You can select PCLKIN to be
either TTL or RS-422 mode and program its polarity through software. In
RS-422 mode, both and PCLKIN– receive the PCLK signal.
PCLKOUT±
Use PCLKOUT± when your camera requires an external pixel clock source.
The NI 1409 can generate variable pixel clock frequencies between 11 MHz
and 40 MHz. You can set PCLKOUT± through your software in TTL and
RS-422 modes.
HSYNCIN±
Use HSYNCIN± when the NI 1409 is in external lock mode. HSYNC is a
synchronization pulse produced at the beginning of each video scan line that
keeps the video monitor horizontal scan rate in step with the transmission of
each new line. You can set HSYNCIN for either TTL or RS-422 mode and
program its polarity through software. In RS-422 mode, both and
HSYNCIN– receive the HSYNC signal.
VSYNCIN±
Use VSYNCIN± when the NI 1409 is in external lock mode. VSYNC is a
synchronization pulse generated at the beginning of each video frame that tells
the video monitor when to start a new field. You can set VSYNCIN to be either
TTL or RS-422 mode and program its polarity through software. In RS-422
mode, both and VSYNCIN– receive the VSYNC signal.
CSYNCIN±
Use CSYNCIN± when the NI 1409 is in CSYNC external mode. CSYNC is a
signal consisting of horizontal sync pulses, vertical sync pulses, and equalizing
pulses only. You can set CSYNCIN to be either TTL or RS-422 mode and
program its polarity through software. In RS-422 mode, both and
CSYNCIN– receive the CSYNC signal.
CSYNCOUT
CSYNCOUT is a TTL output of the internal CSYNC signal. In CSYNC
external mode, CSYNCOUT maps directly to CSYNCIN. In standard mode,
the synchronization circuitry of the NI 1409 generates CSYNCOUT.