NI 5922 Onboard Memory

The NI 5922 allocates at least 640 bytes of onboard memory for each record in a single multirecord acquisition. Samples are stored in this buffer before transfer to the host computer. Thus, the minimum size for a buffer in the onboard memory is approximately 64 samples, because each sample is stored as a 32-bit word. Software allows you to specify buffers of less than these minimum buffer sizes, but only the specified number of points are transferred from onboard memory into the host computer memory.

The total number of samples that can be stored depends on the acquisition memory size option. The maximum number of records in a single multirecord acquisition is equal to the size of the memory option divided by 64 samples. The available memory options are 2 MS, 8 MS, and 64 MS per channel.

Triggering and Memory Usage

During an acquisition, samples are stored in a circular buffer that is continually rewritten until a trigger is received. After the trigger is received, the NI 5922 continues to acquire posttrigger samples if you have specified a posttrigger sample count. The acquired samples are placed into onboard memory. The number of posttrigger or pretrigger samples is only limited by the amount of onboard memory.