Purchase now: Wago 750-450 Resistance Input Module
Purchase now: Atlantech Drives provides you the Wago 750-450, a versatile **4-Channel Analog Input Module** designed for **Resistance Measurement**. Unlike dedicated RTD modules that output temperature in °C, the 750-450 reads raw resistance values (Ohms). It is typically configured to read potentiometers or resistive sensors in ranges like **0 … 1.2 kΩ**. This makes it ideal for reading linear position transducers (linear pots), damper position feedback, or specialized NTC thermistors where the PLC calculates the temperature curve.
Technical Specifications and Resolution
The module allows for the direct connection of 4 resistance sensors using a **2-wire connection** technique. It features a high resolution of **16 bits**, providing extremely precise measurements. The internal electronics supply a constant measurement current to the sensor. The inputs are short-circuit protected. It is packaged in the standard 12mm DIN-rail housing, offering high channel density for resistive applications.
- Part Number: 750-450.
- Channels: 4 Analog Inputs.
- Signal Type: Resistance (0…1.2 kΩ typical).
- Connection: 2-Wire (Common Ground).
- Resolution: 16 bits.
- Conversion Time: ~10 ms.
- Measurement Current: 0.5 mA.
- Error Limit: < +/- 0.1 %.
- Wire Connection: CAGE CLAMP®.
Expert Tips: Compensating Lead Resistance
Accuracy depends on the wiring. Expert Tip: Because the 750-450 uses a **2-wire** method, the resistance of your copper cables is added to the sensor reading. For a 1.2 kΩ potentiometer, a 2 Ohm cable resistance is negligible. However, if you are measuring low resistance values with precision requirements, you must calculate the wire resistance (or measure it by shorting the cable ends) and subtract this «Offset» value in your PLC logic code.
Frequently Asked Questions (FAQs)
Q: Can I use this for PT100 sensors?
A: You *can*, but it’s not the best choice. A PT100 changes only 0.385 Ohms per degree. The 2-wire lead resistance error of the 750-450 will introduce significant temperature errors. Use the 750-460 (PT100 3-wire) module for temperature instead.
Q: How fast is the update?
A: The conversion time is roughly 10ms per channel. For 4 channels, the total cycle time is around 40ms, which is sufficient for thermal or mechanical position monitoring.
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