20
The device and principle of operation L-502.
The presence of the
ADSP-BF523 signal processor with RAM (
modification L-502-P-
░
-
░) is
considered justified for those users who want to get a maximum of on-board signal processing
capabilities on-board, as well as advanced users to have their own low-level processor
programming, possibly using a JTAG emulator.
The presence of galvanic isolation (modification L-502-
░
-G-
░) is considered necessary if the
sources of L-502 input signals and the load circuit of the output signals are not isolated from the
ground and, at the same time, directly (electrically short) are not connected to the case of the system
unit. The galvanic isolation in L-502 provides isolation of all circuits on the contacts of the internal
and external signal connectors and the inter-module synchronization connector
) relative to all circuits of the computer. The signal chains are not isolated between each
other.
The presence of a 2-channel DAC (modification L-502-
░
-
░
-D) is necessary if in your task it
is necessary to reproduce the output analog voltage levels or temporary voltage functions.
ADC 16 bits with a conversion frequency of up to 2 MHz with 16/32-channel circuit
switching (up to 16 differential channels, up to 32 with a common ground) with voltage subbands ±
10 V, ± 5 V, ± 2 V, ± 1 V , ± 0.5 V, ± 0.2 V has an analogue path improved with regard to L-7xx
for the following parameters:
•
The resolution of the ADC is increased and the signal-to-noise ratio is improved due to the
increase in the ADC bit depth, the quality of the analog path, and also at low data acquisition
frequencies due to the built-in hardware averaging of the sample data within the same channel scan
cycle.
•
The interchannel passage for the same test conditions is reduced together with L-7xx: the same
impedances of signal sources and channel switching frequency. In particular, the advantage of L-502
on lower sub-ranges of voltages of ± 0.5 V, ± 0.2 V is gigantic with regard to L-7xx for the same
application conditions.
•
The range is ± 10 V compared to ± 5 V in L-783 (M).
Along with the obvious progress in the characteristics of the ADC in L-502, there are trade-offs in
the following characteristics with regard to L-7xx:
•
Maximum ADC conversion frequency is limited by 2 MHz (in L-783(M) – 3 MHz).
•
Limited to ± 1 V operating range of the input signal at the inputs Y and GND32 (for details, see
).
Instrumental DAC 16 bits 2 channels ± 5 V compared to DAC 12 bits in L-7xx has a much
better resolution, a larger working output current, normalized high-speed transients associated with
the transition from one sample to another, which allows using this DAC in applications, the quality
of the functional generator required from the DAC
. Synchronous (streaming) up to 1 MHz per
channel or asynchronous mode on the selected DAC channel is possible, including mixed
synchronous-asynchronous mode on different channels.
Digital input, up to 18 lines, synchronous mode up to 2 MHz or asynchronous. In
synchronous mode, the stream from digital lines is synchronous with the ADC stream, but separate
and independent of the settings of the ADC data collection frame (the frequency of data collection
by digital lines is set separately and does not depend on the ADC frame settings). Programmable
pull-up resistors to a high logic level on digital inputs.
Digital input, 16 lines. Synchronous as synchronous output up to 1 MHz, and asynchronous is
possible. With synchronous output, the frequency is matched to the frequency of the DAC output.
The output enable allocated for the low and high byte increases the flexibility of using digital lines,
4
Strictly speaking, for qualitative sound applications to the DAC, even more stringent requirements are imposed in comparison
with the requirements for the function generators.
