Example: Transmit weight in decimal tons and as 4-20 mA with overweight alarming
Application: Digitally transmit weight in metric tons with 3 decimal places using a 3 mV/V load
cell. Also output weight from 0 to 5.000 tons as a 0-10V signal. Apply 10V excitation. At a load
of 5.000 tons, the load cell output will be 30 mV. Alarm weight over 4.000 tons, but wait for 8
readings over this limit (or 15 msec) so as not to alarm on a noise spike.
Solution:
• Jumper signal conditioner for 50.000 mV range. Set power supply to 10V excitation.
• Under “Input+Display” tab, set Mode to Strain, range to 50.0mV, decimal point to 3 places,
and “50/60 Hz Line Freq” to 60 Hz to reject 60 Hz noise.
• Under Scaling tab, if “Scale, Offset” method is selected, set Scale to 0.16667. The reason is
that we want 30000 input counts to correspond to 5000 output counts.
• Under Scaling tab, if Coordinates is selected, set “High In” to 30.000 mV and “High Read”
to 5.000 tons.
• Under “Relay Alarms” tab, enter 4.000 tons for Setpoint 1 and 8 readings to alarm.
• Under “Analog Out” tab, set Range to “0-10V Voltage”, “Lo Range Reading” to 0.000 tons
and “Hi Range Reading” to 5.000 tons.
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