CEDAC20 device is euromechanical version of CDAC20. Besides of mentioned this version hasn't internal connection of DAC output with 6th input of ADC. It provides an additional ADC input to user. All the rest parameters are identical for both versions and these devices have the single description. The reason for designing of euromechanical version is the following. At the time our laboratory is developing a power supply for main magnets of VEPP-2000 installation. This power supply must provide 10KA output current with high stability (0,01% and better). All control electronics for this power supply is implementing in euromecanics.
CEDAC20 device is intended for control of precise (0,01% or better) controlled
power supplies. It may be used as general purpose device with precise DAC
and 5-channel precise ADC on-board. The device has optoisolated input and
output registers on-board. It gives an opportunity to build simple systems
with the single devices. You can read a detail description of device in
pdf-file.
The device consist of:
- 1-channel 20-bits bipolar DAC;
- 5-channels ADC;
- 8-channel optoisolated output register;
- 8-channel optoisolated input register;
- CANBUS interface for communication with control computer;
- embedded microcontroller.
An user can use CEDAC20 both precise general
purpose digital-to-analog converter and functional generator. An embedded
microcontroller may store up to 8 files which describes changing output
voltage in time. Embedded processor provides linear interpolation of output
voltage between characteristic points. All devices in network or programmable
group of devices may be started by single broadcast message.
6-channels ADC design is based on delta-sigma ADC chip
and analog multiplexers. Actually the device have 8 input channels and all
of them are identical for programmer. But, three channels have on-board
connections. 6th and 7th channels connected to precise reference source
and "zero". These connections are used by microprocessor to implement procedure
of "system calibration" which highly improves accuracy of ADC. An embedded
microprocessor provides multichannel (from 1 up to 8) measurements or fast
measurements of single channel. Measured values may be sent to a control
computer or may be stored in on-board memory. Stored values may be sent
to a control computer after special request from network. Measurements of
all devices in network or programmable group of devices may be started or
breaked by single broadcast message.
An analog part of device is galvanically isolated from
digital part.
Parameters of CEDAC20:
- resolution of DAC - 20 bits and sign;
- accuracy of DAC - 0,01%;
- resolution of ADC - 24 bits;
- accuracy of ADC - 0,003%;
- input range of ADC - 10V;
- output range od DAC - 10V;
- channels of output register 8;
- channels of input register 8
Victor Kozak, Novosibirsk, 20-may-2014.
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