BEKA BA526C, Руководство пользователя

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1. DESCRIPTION
The BA526C is a panel mounting loop powered
4/20mA combined bargraph and digital indicator.
The one hundred segment bargraph provides a
quick indication of input current magnitude and
trend, supported by an accurate digital display
which may be calibrated in engineering units.
The BA526C is a second generation instrument
which, although having additional functions,
remains compatible with the original BA526B.
The main application of the BA526C is to display a
measured variable or control signal in a process
area. The zero and span of the digital display are
independently adjustable so that the indicator may
be calibrated to display any 4/20mA variable in
engineering units. The analogue display shows
the 4/20mA input on a single or double 100
segment bargraph which may be fitted with a
custom scale to indicate the units of measurement.
Both the bargraph and digital display may be offset
to indicate deviation from a specified input current.
The indicator is housed in a robust 144 x 48 panel
mounting DIN enclosure with an IP65 sealed front.
2. OPERATION
Fig 1 shows a simplified block diagram of a
BA526C. The 4/20mA input current flows through
resistor R1 and forward biased diode D1. The
voltage developed across D1, which is relatively
constant, is multiplied by a switch mode power
supply and used to power the instrument. The
voltage developed across R1, which is proportional
to the 4/20mA input current, provides the input
signal for the analogue to digital converter.
Fig 1 Simplified block diagram of BA526C
Each time a 4/20mA current is applied to the
instrument, initialisation is performed. After a short
delay the following display sequence occurs:
-1.8.8.8.8 Display test in which
all segments of the
display are activated
for 0.5 seconds.
Blank display For 0.5 seconds.
Negative signs For 3 seconds.
cycled
Input current Using calibration
display in information stored in
engineering instrument memory.
units.