User manual

Chapter 3 Software Overview

UseCase#3

The user generates a single trigger pulse event on two physically

distributed data acquisition systems.

A user wants to generate a sine wave at location A and make buffered

analog input measurements at location B at precisely the same time.

The sine wave generated at location A affects the measurements made

at location B.

The software program flow is as follows:

1. Initialize the clock for this application.

• Specify the synchronization signal source (PFI line, RTSI line).

• Specify the synchronization method.

– If source is PPS, read the current time from the GPS receiver

via a serial port and set it as the initial DHMS value of the

clock, or choose any arbitrary value. Initialization will take

about 2 seconds. For more information on initializing the

clock with PPS, refer to the SetUpClockUsingPPS section.

– If source is IRIG-B, simply wait for 2 seconds after

programming the hardware. The clock will automatically

synchronize to the GPS signal.

• Route the PPS output of the receiver to one of the counter source

lines for the TIO counter to receive.

2. Set up the counter.

• Configure one of the counters for single pulse generation.

– Application type = single pulse generation

– Source = source line carrying the PPS signal

• Specify the pulse delay.

– Translate the actual trigger time into the number of seconds

since the beginning of the current year (x seconds).

– Read the clock value (y seconds).

– Specify pulse delay (x-y).

• Specify the appropriate trigger pulse width.

• Arm the counter.

• Read the clock value.

– If the clock value is still y seconds, you are done.

– Iftheclockvalueismorethany seconds, reset the counter and

return to the beginning of step 2.