Promax RW-ST01A Load Cell Amplifier 2.0mV/V Waterproof IP65 Surface mount

Specifications

• Accuracy: Better than 0.3% F.S.
• Loading Capacity: Parallel connection max. 4 x load cells of 350Ω
• Sensitivity: 2.0mV/V ±10%
• Input Signal: mV Signal
• Output Signal: Default 4-20mA and 0-5(10)V (switchable)
• Voltage output impedance: >5kΩ
• Current output impedance:＜500Ω
• Voltage Zero adjustment: Fine: 10% F.S. Rough: 40% F.S.
• Voltage Span adjustment: 10% F.S.
• Current Zero adjustment: 10% F.S.
• Current Span adjustment: 10% F.S.
• Power Supply: DC24V (18-27VDC range)
• Max. power consumption: 4W(4 x 350Ω sensor, output 20mA.)
• Load Cell Excitation Voltage: 5V+ ±5%(Suitable for 5-12V excitation volt. sensor)
• Load Cell Excitation Current:＜60mA
• Enclosure Material: ABS
• Net Weight: 100g
• Installation Hole Size: 2×Φ3
• Enclosure Protective Class: IP65
• Installation Mode: Enclosure fixed installation
• Dimension(LxWxH): 115x58x33mm
• Working Temperature: 0-50℃/85%RH, non-condensation.
• Storage Temperature: -20- +80℃/85%RH, non-condensation.

Features:

• Waterproof design, good sealing of enclosure and cable joint.
• 2.0mV/V±10% sensitivity, better than 0.1% F.S. accuracy.
• Internal precision amplifying and conversion circuits.
• Zero and span are easy to be adjusted through potentiometer terminals.
• 4-20mA current and 0-5V, 0-10V voltage output in one amplifier, the output signal is selectable through the switch button.

Applications

• Industrial Automation: Direct integration of load cells into Siemens, Allen-Bradley, or Delta PLCs.
• Silo & Tank Weighing: Monitoring liquid or grain levels using 4-20mA long-distance transmission.
• Material Testing Machines: High-accuracy stress and strain measurement.
• Smart Conveyor Systems: Real-time dynamic weight sorting on manufacturing lines.

Package Includes

• 1 x Promax RW-ST01A Load Cell Amplifier 2.0mV/V Waterproof IP65 Surface mount

Frequently Asked Questions (Technical FAQ)

• Can I use this with a standard 5V Arduino?
  While the module requires 12-24V to power on, you can read the 0-5V analog output using an Arduino's analog pins. Do not use the 0-10V output directly on a 5V board.
• How do I choose between 4-20mA and 0-10V output?
  Use 4-20mA for long cable runs (highly immune to electrical noise) and 0-10V for short runs directly into local DAQ systems.
• Is this compatible with 1.0mV/V or 3.0mV/V load cells?
  Yes, the internal potentiometers allow you to tune the gain to accommodate load cells ranging from 1.0mV/V to 3.0mV/V.
• How do I calibrate the zero point?
  Remove all weight from the load cell, and adjust the 'ZERO' potentiometer with a small flathead screwdriver until the output reads exactly 4mA or 0V.
• How do I calibrate the span (max weight)?
  After zeroing, place a known calibration weight on the scale and adjust the 'SPAN' potentiometer until the output matches the expected voltage or current.
• Why is my output reading fluctuating wildly?
  This is usually caused by unshielded cables, ground loops, or mechanical vibrations. Ensure you are using shielded cables and the shield is grounded at one end only.
• Can I connect multiple load cells to one amplifier?
  Yes, but you must use a load cell junction box to sum the signals before feeding them into this single amplifier.
• What does IP65 mean for this module?
  IP65 means it is completely dust-tight and protected against low-pressure water jets from any direction. It is safe for factory washdown areas.
• Does this module output digital data like I2C or SPI?
  No, this is a purely analog transmitter. If you need digital data, you must feed the analog output into an ADC or PLC.
• What is the maximum distance for the 4-20mA signal?
  Depending on cable quality and interference, 4-20mA signals can easily travel hundreds of meters without data loss.
• Can I power this from my PLC's internal 24V supply?
  Yes, as long as your PLC's power supply can provide the necessary current (typically <50mA per module).
• Why is my output stuck at 0V/0mA even with weight applied?
  Check your load cell wiring. Reversing the excitation or signal wires will cause the amplifier to output zero.
• Is the output isolated from the input?
  Standard versions do not have full galvanic isolation. Ensure your system grounds are properly tied to prevent ground loops.
• What type of cable should I use to connect it to the PLC?
  Use twisted-pair, copper-braid shielded industrial cable (e.g., 22 AWG or 24 AWG) to minimize EMI.
• Can I use this for dynamic weighing on a moving conveyor?
  Yes, analog transmitters have near-instantaneous response times compared to digital filtering chips, making them ideal for dynamic weighing.
• My load cell has 6 wires instead of 4. Can I use it?
  Yes. A 6-wire load cell has Sense+ and Sense- wires. You can simply tie Sense+ to Excitation+ and Sense- to Excitation- at the amplifier terminals.
• What is the resolution of this amplifier?
  As an analog device, its resolution is essentially infinite. The actual system resolution will depend on the ADC bit-depth of your receiving PLC.