BSL PRO Software Guide - Biopac

Acquisition Functions 85Acquisition LengthTo set the duration of an acquisition, enter a number in the Acquisition Length box. By default, 60 minutes of data will berecorded.The MP UNIT will automatically limit the maximum recording length to the amount of available memory on the target storagedevice (PC Memory or Hard Disk). The default is to record one acquisition of the duration specified in the Acquisition Lengthbox.The pull-down menu to the right of the Length box allows you to scale the duration of the acquisition in terms of milliseconds,seconds, minutes, hours, or samples. Changing this option will not change the length of the acquisition, only the units used todescribe it. Thus you can describe the same acquisition as lasting 30 seconds, or 0.5 minutes, or 30,000 milliseconds. Scaling theduration of an acquisition in terms of samples is essentially the same as the time scaling options, except the length of theacquisition will be expressed in the total number of samples to be collected on one channel.The maximum acquisition length and, on the PC only, current acquisition requires, are calculated based on all the activechannels, the types of channels activated (analog or calculation), and the other acquisition setup parameters. This referenceinformation is displayed above the Acquisition Length section of the Setup Acquisition dialog. The BSL PRO requires 2 bytesper analog sample and 8 bytes per calculation sample. The memory calculation does not include approximately 25KB per file forheader information.In the default Append mode, “max acquisition length” reflects the total available length—if you are going to record more thanone segment, you need to set the acquisition length so that the combined length of all appended segments falls within thespecified maximum length.If you are using the Repeat function, the memory calculation is based on one acquisition; you will need to multiply by thenumber of repetitions to calculate the total memory required.Regardless of what scale you use to determine the length of acquisition, the MP36/35 will stop acquiring data when the value inthe Acquisition Length box is reached. You may also stop the acquisition at any time by clicking on the button in thelower right hand corner of the graph window.Note The Acquisition Length parameter has a somewhat different interpretation in the Record last mode; see page679 for more information about settings for this mode.