Delta 211 Series Specifications download pdf (Page 17)

DVP201/202/211LC-SL Load Cell Module Operation Manual

3.4 Selecting a Load Cell Sensor

1. Exciting voltage:

An excitation voltage is external power provided for a load cell sensor. The maximum voltage that a sensor

can accept is specified in the specifications for the sensor. The exciting voltage that a load cell module

provides is +5 V, and therefore a sensor which can accept a voltage greater than 5 V can be used.

2. Eigenvalue

A load cell sensor uses a bridge circuit. If a load cell is under pressure, SIG+ and SIG- will output voltages

which are in proportion to force. An eigenvalue determines the characteristics of the output of a load cell

sensor. The unit used is mV/V. If a load cell receives external force, it will output low voltage.

Output a sensor: (Force/Maximum rated load)×(Exciting voltage×Eigenvalue)

Example: The eigenvalue of a sensor is 2 mV/V, and the maximum rated load of the sensor is 10 kg. The

voltage provided by a module is 5 V. The voltage to which the maximum rated load corresponds is 10 mV.

If the load of the sensor is 1 kg, the voltage that the sensor outputs will be 1 mV. The eigenvalue that the

module can support is 80 mV/V. The sensors whose eigenvalues are less than 80 mV/V can be used.

3. Maximum rated load

When users select a load cell module, they have to consider factors such as loads, tares, vibrations, and

shocks. The closer the load on a load cell sensor is to the maximum rated load specified in the

specifications for the load cell sensor, the more accurately the load is measured.

4. Four-wire configuration/Six-wire configuration

There are two ways to wire a load cell sensor. They are a four-wire configuration and a six-wire

configuration. A load cell module provides power for a load cell sensor by means of EXC+/EXC-. However,

there is impedance between the load cell module and the sensor. The voltage that the sensor actually

receives is less than the voltage provided by the module. The output terminals SIG+ and SIG- on a sensor

have relations with the voltages received. If the distance between a module and a sensor is short, the

impedance between the module and the sensor will be small, and a four-wire configuration can be adopted.

If the distance between a module and a sensor is long, a six-wire configuration can be used to reduce the

error resulting from the impedance between the module and the sensor.

5. Estimating precision

The precision of a load cell module is 0.04%. The maximum rated load of a load cell sensor multiplied by

0.04% is the maximum precision that a load cell module can resolve. (The measurement time set by

default is 50 milliseconds.) If the measurement time set is longer, the precision presented will increase.

When users select a load cell sensor, they have to check whether the conversion time of the load cell

sensor and the precision of the load cell sensor meet their requirements.

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Delta 211 Series Specifications Page 17