User manual

RT USB3000 Technical Description and User Manual Rev. 4.1. 8 of 18
3.3. “Logic Analyzer” mode
In the “Logic Analyzer” mode RT USB3000 device provides the input into a PC of digital signals
from 10 input digital lines with the sampling frequency up to 6 MHz.
The data enters into a PC in the form of double-byte words, their 10 least significant bits
correspond to the logic state on 10 input digital lines of the device ("1" - corresponds to high level at
the input). The 6 most significant bits are always equal "0".
From the point of view of a user this mode is similar to the "ADC" mode. A user sets the sampling
frequency, and in the control table he sets only one channel which corresponds to the data input not
from ADC, but from the digital lines.
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 digital inputs can be continuously recorded in PC RAM in real-time
and simultaneously stored on the hard drive.
Three operation modes described above can be combined as follows:
3.4. “ADC + DAC” mode
In this mode RT USB3000 device provides duplex input/output of the information. The data input
from 8 input channels of ADC with the conversion frequency up to 3 MHz is parallel with the data
output to a 2-channel DAC with the conversion frequency up to 100 kHz.
Duplex communication between the PC and the RT USB3000 device can be carried out
continuously without any gaps and time limits.
3.5. “Logic Analyzer + DAC” mode
In this mode RT USB3000 device provides duplex input/output of the information. The data input
from 10 digital inputs with the sampling rate up to 6 MHz is parallel with the data output to a 2-channel
DAC with the conversion frequency up to 100 kHz.
Duplex communication between the PC and the RT USB3000 device can be carried out
continuously without any gaps and time limits.
In all the above described 5 operating modes an asynchronous access from a PC to 10 input and
8 output digital lines of the device is possible. For example, the device operates in “ADC” mode –
collects the data from 8 input analog channels and transmits it to a PC. A user can scan the status of
10 digital inputs and set 8 output digital lines to a required logic state without the interruption of the
data acquisition from ADC.