6841 Programmable transmitter for strain gauge sensors0 pages

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6841 Programmable transmitter for
strain gauge sensors
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Strain gauge sensors with 4- or 6-wire connection
Excitation voltage 10 V to sensors, max 150 mA
Red LED display on the front panel
Settings via front panel keys
Output 0/4..20 mA, 0..10 V
Serial communication RS-485
2 alarm relays
Taring via front panel keys or external switch
Measuring accuracy < 0,05 %
Power supply 12..32 VDC or 85..240 VAC
Linearisation 6 points

The versatile transmitter 6841 is designed for strain gauge
sensors. Strain gauge sensors can be connected with 4 or 6
wires. The 6-wire connection is recommended for applications
requiring very high accuracy. The transmitter provides 10 V
excitation voltage for the sensors, max. four 350 ohm sensors.
The transmitter 6841 includes output 0/4-20 mA/ 0-10 V, 2
alarms or serial output RS-485 as standard.
Display scaling and taring is easy via front panel keys. Scaling
can be carried out in two different ways, either by applying the
mV/V values of the bridge or using the teaching function. The
teaching is done by first loading the sensors with the min.
weight and then with the max. weight, after which the transmitter
will automatically calculate the scaling. Additional teaching
points can be utilized to improve linearity.

In applications where the sensor loading is not in balance a
separate serial connection unit of the sensors, 20 SA-4, can be
used to prevent the nonlinearity caused by the imbalance.
There are two power supply alternatives: one for line voltage
85..240 VAC and the other for 12..32 VDC or 24 VAC, both
galvanically isolated from input and outputs. Analog conversion
is done by a 16-bit A/D-converter (resolution 1/64000) and the
number of measurements is 3 per second. The display can be
damped by a digital filter if necessary. The number of decimals
on the display is selectable.

Schematic Drawing of Transmitter 6841
Power supply:
85..240 VAC or
12..32 VDC/ 24 VAC

Configuration,
display scaling
and taring via
front panel keys

Tare or
hold
Alarm 1

60.00

Alarm 2
+10 V

I = max. 150 mA

Microprocessor

+ Sense

ADC
mV-output
- Sense

1-4 sensors

16 bit

Transmitter 6841

Serial output RS-485
Output 0/4..20 mA
or 0..10 V