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A load cell transmitter with 4-20 mA output must satisfy two different interfaces: the strain-gauge bridge at its input and the receiver at its output. Checking only the PLC current range misses excitation limits, bridge loading and available supply voltage.
Load Cell Transmitter With 4-20 mA Output: Check Both Sides
| Connection | MV-WI0014 data | Purchase check |
|---|---|---|
| Bridge | One 350 ohm analog cell; rated input 1-3 mV/V. | Do not assume a summing box permits several parallel cells. |
| Excitation | 5 V supplied to the sensor. | Confirm the chosen cell permits this excitation. |
| Supply | 8-30 V DC. | Account for the permitted receiver load at the actual voltage. |
| Receiver | 4-20 mA; listed 0-500 ohm load with restrictions below 10 V. | Review the full circuit and terminal drawing rather than combining separate maxima. |
The METRAVON MV-WI0014 specification covers this analog configuration. It does not establish an RS485 port or Modbus RTU support. Also confirm the supply and signal terminal arrangement; a current output does not by itself identify a two-wire loop-powered instrument.
Write Down What 4 mA and 20 mA Mean
Define the physical load at each endpoint and whether the transmitted quantity is gross or net. For linear scaling, the fraction of span is (I - 4 mA) / 16 mA. Apply that fraction to the agreed load interval in the receiver. This calculation does not compensate for an unsuitable sensor, mechanical binding or transmitter error.
Keep the stated MV-WI0014 1% linearity figure visible in selection. Obtain its reference basis and test conditions before using it in a system error budget. Increasing the PLC display resolution cannot improve the analog transmitter's underlying linearity.
Check Weight, Current and PLC Value Together
Apply appropriate reference loads using the installed mounting arrangement. Record the current and PLC value at zero, intermediate loads and span, then unload and repeat. Adjust through the documented zero and span procedure, retaining the as-found results.
Agree how the receiver detects an interrupted or invalid measurement. Do not invent a specific fault-current convention where the transmitter documentation has not confirmed one. Test the actual failure response safely before relying on the signal for automatic operation.
Analog-Input Questions
Q1. Can four 350 ohm cells be attached through a junction box?
The published drive is for one cell. Parallel bridges increase excitation demand, and a passive box does not increase available drive. Select a suitable multi-cell transmitter or obtain explicit approval.
Q2. Is a nominal millivolt calculation enough for calibration?
No. Sensitivity and excitation help establish input compatibility, but actual load-to-signal behaviour includes the installed mechanics and individual sensor response. Use the agreed physical reference for the completed system.
Summary
Confirm the bridge, supply, receiver resistance and error allowance before purchasing. Include those details in an MV-WI0014 enquiry, with the intended load assigned to each current endpoint.
