NI 5922 Multiple-Record Acquisition

The NI 5922 supports multiple-record acquisitions, which allow the capture of multiple triggered waveforms without software intervention. In this mode, the digitizer automatically begins a new acquisition in a new memory record immediately after finishing the previous one. Multiple-record acquisitions can quickly acquire numerous triggered waveforms because they allow hardware rearming of the digitizer. Between each record, however, there is a dead time during which no triggers are accepted. During this time, the memory controller sets up for the next record. There is also a holdoff from the last trigger in a record to the start of a new record. This means that the actual dead time is the greater of the between-record dead time and the holdoff time. There may also be additional dead time while the minimum number of pretrigger samples are being acquired. To increase the dead time between records, use the trigger holdoff feature.

The number of records that can be acquired varies depending on the memory option that the device has. Currently the NI-SCOPE software has a limit of 100,000 records that can be acquired without fetching. However, if the records are fetched while they are being acquired, more records can be acquired. Refer to Acquiring More Records Than Fit in Digitizer Memory and SMC-Based Digitizers Timing Diagram for more information.