Meilhaus RedLab 1008, User Manual

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Chapter 3
Functional Details
Theory of operation - analog input acquisition modes
The RedLab 1008 can acquire analog input data in three different modes – software paced, continuous scan, and
burst scan.
Software paced mode
In software paced mode, the RedLab 1008 gathers data in a single acquisition or as a group of single
acquisitions. An analog-to-digital conversion is initiated with a software command, and the single data point
result is returned to the host. This operation may be repeated until the required number of samples is obtained
for the channel (or channels) in use. Software pacing is limited by the 20 mS round-trip requirement of a USB
interrupt-type endpoint operation. This yields a maximum throughput in software paced mode of 50 S/s.
Continuous scan mode
In continuous scan mode, the RedLab 1008 gathers data in a single-channel or multi-channel sequence. This
sequence converts, transfers, and stores data to a user buffer until the scan is stopped. In this mode, digitized
data is continuously written to an on-board FIFO buffer. This FIFO is serviced in blocks as the data is
transferred from the RedLab 1008 to the user buffer in the host PC.
The maximum continuous scan rate of 1.2 kS/s is an aggregate rate. The total acquisition rate for all channels
cannot exceed 1.2 kS/s. You can acquire data from one channel at 1.2 kS/s, two channels at 600 S/s and four
channels at 300 S/s. You can start a continuous scan with either a software command or with an external
hardware trigger event.
Burst scan mode
In burst scan mode, the RedLab 1008 gathers data using the full capacity of its 4 K sample FIFO buffer. You
can initiate a single acquisition sequence of one, two, or four channels by either a software command or an
external hardware trigger. The captured data is then read from the FIFO and transferred to a user buffer in the
host PC.
Since the data is acquired at a rate faster than it can be transferred to the host, burst scans are limited to the
depth of the on-board memory. As with continuous mode, the maximum sampling rate is an aggregate rate.
Consequently, the maximum burst mode rates are 8 kS/s, 4 kS/s and 2 kS/s for one, two and four channels,
respectively.