User's Manual

Chapter 2 Function Reference — Select_Signal
NI-DAQ FRM for PC Compatibles 2-384
© National Instruments Corporation
Use source = ND_NONE to stop the device from driving the RTSI clock line.
When source =
ND_BOARD_CLOCK, this device drives the signal on the RTSI clock line.
For DAQArb 5411 devices, the board clock is a 20 MHz clock.
signal =
ND_BOARD_CLOCK
Use source = ND_BOARD_CLOCK to stop the device from receiving the clock signal from the
RTSI clock line.
Use source =
ND_RTSI_CLOCK to program the device to receive the clock signal from the
RTSI clock line.
signal =
ND_PLL_REF_SOURCE
Use ND_NONE for internal calibrated reference.
By using
ND_IO_CONNECTOR, you can select an external reference clock to be the source for
the phase-locked loop (PLL), or you can use
ND_RTSI_CLOCK when running at 20 MHz to
be the reference clock source for the PLL. By default, NI-DAQ selects the internal reference.
Special Considerations when source = ND_CONVERT
When you enable the convert signal to go out on
PFI_2
or any of the RTSI lines, there will
be a pulse prior to the start of data acquisition. This is the side effect of programming the
device for data acquisition, and the receiver of the signal should keep this in mind. For
example, to synchronize two devices using the convert signal, you should also make them
share the start trigger signal. so that the spurious convert pulse generated by the controlling
device is ignored by the controlling device.
source sourceSpec
ND_BOARD_CLOCK ND_DONT_CARE
ND_RTSI_CLOCK ND_DONT_CARE
source sourceSpec
ND_RTSI_CLOCK ND_DONT_CARE
ND_IO_CONNECTOR ND_DONT_CARE
ND_NONE (default) ND_DONT_CARE