User manual

RT USB3000 Technical Description and User Manual Rev. 4.1. 7 of 18
3. Operating modes
The device hardware solution and standard software make it possible to implement the following
operating modes:
3.1. “ADC” mode
In the “ADC” mode RT USB3000 device provides the multi-channel input of analog signals with
the ADC frequency up to 3 MHz and the channel switching frequency up to 3 MHz.
Data from the ADC are signed double-byte integers ranging from -8000 (corresponds to the
voltage of -5V at the analog input) to 8000 (corresponds to the voltage of +5 V at the analog input).
Before entering data into the PC it is possible to perform program adjustment of the values acquired
from ADC, with the use of calibration factors recorded in the ROM of the device at the stage of
adjustment by the manufacturer. The user can, if necessary, use his own calibration factors for
program adjustment.
The device has 8 differential analog inputs. The user sets the frequency of the ADC and the so-
called “control table”. i.e. the array of channel numbers according to which the device will perform
recurrent data acquisition. For example, the user sets the ADC frequency of 3 MHz and the control
table containing the numbers: 0, 1, 2, 0, 8, 2. In this case, the device will digitize channels 0, 1, 2, 0,
8, 2, 0, 1, 2, 0, 8, 2 ... etc, switching them at the rate of 3 MHz. If only one channel is set in the table,
the device will digitize only this channel with a given frequency.
The data acquisition can be started by giving a command from a PC or by the external signal – a
digital pulse on "SYN" contact of the
analog port of the device.
The data acquired from the ADC can be continuously recorded in PC RAM in real-time and
simultaneously stored on the hard drive.
3.2. “DAC” mode
In the “DAC” mode RT USB3000 device provides the 2-channel output of analog signals with the
DAC frequency up to 100 kHz and the channel switching frequency up to 100 kHz.
It is possible to perform program adjustment of the values delivered to the DAC, with the use of
calibration factors recorded in the ROM of the device at the stage of adjustment by the manufacturer.
The user can, if necessary, use his own calibration factors for program adjustment.
The DAC channel number is coded directly in the data. Therefore, in order to work with the DAC,
the user should set only DAC operation frequency and prepare in the PC memory the buffer with the
data which are to be transferred.
Data can be continuously transmitted to the DAC from the PC RAM (or hard disk) in real-time.