BEKA BA678C, Руководство пользователя, Страница: 4 / 27

1. DESCRIPTION
The BA678C is a panel mounting 4/20mA loop
powered temperature transmitter with a large easy to
read display.
The instrument, which is HART

enabled, may be conditioned on-site to operate with
most
common thermocouples and resistance
thermometers and will provide a linear 4/20mA output
proportional
to temperature, plus a digital
temperature display. Voltage and resistance inputs
may be scaled allowing the BA678C to display
variables other than temperature such as position
and weight.
Optional factory fitted alarms provide two galvanically
isolated
solid state outputs that may be
independently configured for high or low operation.
For installation in poorly illuminated areas, an
optional factory fitted loop powered display backlight
is available.
Fig 1 Simplified block diagram
2. DOCUMENTATION
This instruction manual describes the installation and
configuration of the BA678C Indicating Temperature
Transmitter.
The transmitter is HART Registered and is compliant
with HART protocol standard revision 7. HART

commissioning information is included in the BA47X/
67X Indicating Temperature Transmitter
HART

Interface Guide which may be downloaded from
www.beka.co.uk/manuals
3. OPERATION
Fig 1 shows a simplified diagram of the BA678C
Indicating Temperature Transmitter.
The input,
which may be from a resistance thermometer,
thermocouple, or a dc voltage or resistance, is
digitised and transferred to the instrument processor
via an optical isolator. The processor linearises the
input signal, displays the resulting temperature in the
selected units and controls the 4/20mA output
current.
3.1 Controls
All functions of the transmitter may be configured via
the front panel push buttons.
Buttons respond
within 0.5 seconds of being operated and unless
continuously pushed the transmitter display will
return to the operating mode after 2 seconds.
In the operational mode, i.e. when the transmitter is
displaying the input signal, these push buttons have
the following functions:
Button Function
▼ While this button is operated the transmitter
will show the display corresponding to 4mA
output.
▲
While this button is operated the transmitter
will show the display corresponding to
20mA output.
▼ + ▲ Transmitter displays output current in mA
followed by output as % of the range.
P + ▼ Transmitter displays HART

short address
followed by firmware version number.
P + E Entry to configuration menu. See 6.1.1
When fitted with optional alarms
P + ▲ Entry to alarm set point menu. See 9.3.11
E + ▲ Transmitter displays alarm 1 setpoint
E + ▼ Transmitter displays alarm 2 setpoint
P Activated alarm reverts to the non-alarm
condition for the configured alarm silence
time. See 9.3.10
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