SNV Engineering SNV018EC.XX, Руководство пользователя и инструкция по установке

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S N V 0 1 8 E C . X X
U S E R & I N S T A L L A T I O N M A N U A L
V 3 . 1
© SNV Engineering Ltd
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The card offers 8, 12, 16 or 24 channels of DC current measurement. Low side
terminal is common, hence, card is suitable for high side measurement
(connecting positive cable to the card). Current measurement terminals are
isolated from power supply and bus terminals.
In order to perform the measurements, low thermal drift, shunt resistors are
used. Voltage on them is amplified through precision amplifiers and then sampled
and processed by a 32bit CORTEX-M3 microcontroller at 96MHz.
Figure 2: CMC SNV018EC Functional Diagram.
The microcontroller can deliver measurements through a serial RS485 transceiver
using Modbus protocol. It can also hold values, in order to perform simultaneous
measurements through all the cards in a bus and then retrieve all the
measurements. The microcontroller is also calculating the average of the currents
and of their square, with 1kHz sampling for each channel. The averaging period is
indicated-marked by a master controller broadcast command. Averaged values of
different cards are synchronized and then collected. Bandwidth consumption on
the bus is limited, giving the ability for a prompt response of the rest requests.
An additional input is also implemented to monitor a switch or a sensor acting as
a switch (ex. surge protection, door opening etc.).
Board temperature is also measured and provided
.