Load cells come in two wiring configurations: 4-wire and 6-wire; similarly, weighing modules or transmitters support both 4-wire and 6-wire connections. The choice depends on your hardware requirements. The general rule is: if a load cell supports 6-wire connection, do not use 4-wire; if a 4-wire connection is mandatory, short-circuiting is required.
Most load cells are designed for 6-wire systems. When connected in a 4-wire configuration, the excitation lines (EXC-, EXC+) are shorted to the feedback lines (SEN-, SEN+), respectively. The SEN+ and SEN- lines are used to compensate for line resistance; SEN+ is electrically connected to EXC+, and SEN- is connected to EXC-.
EXC+ and EXC- supply power to the load cell; however, due to line loss between the weighing module and the sensor, the voltage actually received by the sensor is lower than the supply voltage. Every load cell has a specific mV/V characteristic, meaning its mV output signal is closely tied to the received voltage. SEN+ and SEN- essentially form a high-impedance loop within the load cell that feeds the actual voltage back to the weighing module. For example, if EXC+ and EXC- are set to 10V and there is line loss, a sensor rated at 2mV/V would output a maximum signal of (10V - loss) × 2 = 19mV, rather than 20mV. In this scenario, the system treats 19mV as the full-scale output, provided the actual voltage is fed back to the module via the feedback loop. Shorting EXC+ to SEN+ and EXC- to SEN- at the load cell is only appropriate when the distance between the sensor and the weighing module is short and voltage loss is negligible; otherwise, measurement errors will occur.