User manual

Chapter 4: PowerDAQ Software (SDK)
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Method H. Synchronous stimulus/response
operation
This is subset of Method A. Some applications require a analog stimulus
to be applied to a system and a response read. You can do this by
setting the analog input to start the scan from an external clock (CL
Clock line) and the analog output to output the next data point on the
external trigger line pulse. Then connect one of the UCT to start a
countdown from the external trigger line pulse and output to this UCT
to the CL Clock line. When an external trigger pulse is detected, it starts
the countdown and initializes the analog output update. Then the UCT
clocks the CL Clock after the desired delay.
The PowerDAQ board is very flexible and can be configured in many
different ways.
To convert analog input raw values to float voltages use
the PdAInRawToVolts(…)
Note Shared interrupts and IRQ level. PowerDAQ boards
are designed to share interrupts. We do not recommend
PowerDAQ boards to share interrupts with devices like video and
network cards or hard drives. These devices tie up interrupt lines
extensively and can significantly delay interrupt response from a
data acquisition board. Windows 9x/NT/2000 are not real-time
operating systems however your PowerDAQ data acquisition
board is a real-time application. Many motherboard
manufacturers allow you to set up a IRQ level to a particular PCI
slot. If you do not use serial and/or parallel ports you can
disable them and use IRQs 3, 4, 5, 7 for your data acquisition
boards.
TIP