Measurement Computing USB-7204 - Manual (Page 10)

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Chapter 3
Functional Details
Analog input modes
The USB-7204 can acquire analog input data in software paced and continuous scan modes.
Software paced
You can acquire one analog sample at a time in software paced mode. You initiate the A/D conversion by
calling a software command. The analog value is converted to digital data and returned to the computer. You
can repeat this procedure for each channel desired until you have the total number of samples that you want
from each channel. The maximum throughput sample rate in software paced mode is system-dependent.
Hardware paced
You can acquire data from up to eight channels simultaneously in hardware paced mode. The analog data is
continuously acquired and converted to digital values until you stop the scan. Data is transferred in blocks of up
to 32 samples from the USB-7204 to the memory buffer on your computer.
The maximum continuous scan rate of 50 kS/s is an aggregate rate. You can acquire data from one channel at
50 kS/s, two channels at 25 kS/s, and four channels at 12.5 kS/s. You can start a hardware paced scan with
either a software command or with an external hardware trigger event.
Board components
The USB-7204 components are shown in Figure 2.
1 Trigger/Sync connector 5 Power LED (top) and Status LED (bottom) 8 OEM connector
2 Trigger jumper (P7) 6 USB connector 9 Pins 21-40
3 Sync jumper (P6) 7 Pull-up/down jumper JP2 (Port 0) 10 Pull-up/down jumper JP1 (Port 1)
4 Pins 1-20
Figure 2. Board components