Allocate device memory at PXI 6115

[ruedi]

Hallo,
I am using one PXI 6115 to acquire data. The acquisition is external clocked with 8 MHz. It should be triggered by an external digital trigger, and be able to read pretrigger scans.
Now I have 2 Problems:
1. The Trigger occurs only once a day or once a week. What can I do to prevent my application to run into timeout error ??
2. I want to measure about 200 ms of total time, meaning this are 1.6 million of sampling point per channel. For this reason I tried to allocate device memory, but I am getting always error messages (running in pretrigger mode; Error 10403)
Can anyone give me some hints or tips?
Many thanks Ruediger

[cous]

Hi Ruediger,

The PXI-6115 is capable of doing an 8MHz digitally triggered analog acquisition assuming your system requirements do not restrict the acquisition. Below are answers to your specific questions:

1. Depending on the driver you are using, you can avoid a timeout error:

NI-DAQmx: Setting the timeout limit to -1 will tell the VI to wait indefinitely.

Traditional NI-DAQ: Unfortunately, there isn't an infinite wait time for traditional DAQ VI's, but the input for the timeout limit is a single precision number, so you can make it extremely large (2^32 seconds).

2. You should be able to acquire this much data. How large of a buffer did you use, and did you allocate the memory in the system or on the card? Allocating a larger buffer may eliminate the e
rror.

Thanks for contacting NI,
Marcus G.
Applications Engineer
National Instruments