Simultaneous analog & digital input to PCI-6115, external timing, VB

[poc]

With the PCI-6115, I need to input analog and digital data under control of an external timing pulse. Each time I receive a timing pulse I want to simultaneously sample two analog inputs and one 8-bit digital input port. After a fixed number of acquisitions, stop. The rate of external timing pulses should be up to 1 - 5 MHz. I am programming in Visual Basic using NI-DAQ v. 6.9.2 routines.


I will connect the external timing pulse to one of the PFI pins on the connector. My specific questions are:


-- what is the best sequence of NI-DAQ VB functions to set up the board for acquisition? I assume I will need DIG_Group_Config, DIG_Group_Mode,
DIG_Block_PG_Config, and DAQ_Config.
I need help
specifying the parameters correctly for external timing, for my PCI-6115 board.


-- what functions to arm the board for acquisition, in what order?
[DAQ_Start
or SCAN_Start, DIG_Block_In?]


-- do I need Select_Signal to route the external timing pulse, if so to what signal should it be connected [ND_IN_START_TRIGGER, ND_IN_SCAN_START, or
ND_IN_CONVERT?]
Or, does one of the setup functions do this already?


-- what are the restrictions on the number of samples I can specify, e.g. is digital input restricted to a multiple of 16 and what about flushing the ADC pipeline?

-- anything else I need to take care of?

P. O'Connor, Brookhaven National Lab.

[Filipe A.]

Hello;

That board of yours doen't have digital lines with strobed capabilities. That means the digital lines will be updated through a Software call only, being way slower than your application reuiqres.

The way to go about that is to work with the 6115 acquiring the analog input data and have a 6534 acquiring the digital data. You can synchronize both through the RTSI bus, to have the same clock signal clocking both the analog input and digital acquisition.

Hope this helps.
Filipe A.
Applications Engineer
National Instruments

[Filipe A.]

Hello;

Actually, you can do that. I confused your board model with another one in which you can't perform buffered digital operation.

You will need to make a call to the Select_signal() function. You need to configure its parameters in a way that it will route the AI Scan Start signal to one of the RTSI lines.

After that, you need to call the DIG_Block_PG_Config, and set the reqSource parameter to be the same RTSI line you configured in the Select_Signal() function.

Regarding the correct function call order:
DIG_Grp_Config,
DIG_Block_PG_Config,
DIG_DB_Config,
DIG_Block_In,
DIG_DB_HalfReady,
DIG_DB_Transfer.

Since the Analog Input task is the master of the acquisition, make sure to make all the NI-DAQ funtion calls to configure the digit
al acquisition (the ones I listed above), and then make the calls to configure the Analog Input task.

Sorry for the confusion.
Filipe A.
Applications Engineer
National Instruments