4–20 mA Current Loop Converter
Convert loop current to engineering units (temperature, pressure, level) and back, with percentage, sense-resistor drop and wire-break detection.
Key points
4–20 mA Current Loop Converter: Convert loop current to engineering units (temperature, pressure, level) and back, with percentage, sense-resistor drop and wire-break detection. Formula: Value = LRV + (I − 4mA)/16mA × (URV − LRV). Enter parameters on the DD-CAT IDE online tool page to get results instantly, with a calculation-model diagram that updates with the inputs. NAMUR NE43 defines < 3.6mA as wire break and > 21mA as saturation, which makes instrument diagnostics possible. A 250Ω resistor into a 5V ADC is the simplest front end; its accuracy sets the measurement error, so use 0.1% metal film.
Inputs
Value = LRV + (I − 4mA)/16mA × (URV − LRV)Calculation model (updates with parameters)
| Engineering value | 50.000 °C | |
| Percent of span | 50.00 % | |
| Loop status | Normal (4–20 mA) | |
| 250Ω Sense resistorvoltage drop | 3.0000 V | Scale against this voltage when feeding an ADC directly |
| Max total loop impedance (24V supply) | 1000 Ω | Rough estimate assuming the transmitter needs ≥12V |
Engineering notes
- NAMUR NE43 defines < 3.6mA as wire break and > 21mA as saturation, which makes instrument diagnostics possible.
- A 250Ω resistor into a 5V ADC is the simplest front end; its accuracy sets the measurement error, so use 0.1% metal film.
FAQ
- What is 4–20 mA Current Loop Converter for?
- Convert loop current to engineering units (temperature, pressure, level) and back, with percentage, sense-resistor drop and wire-break detection.
- What is the formula for 4–20 mA Current Loop Converter?
- Core formula: Value = LRV + (I − 4mA)/16mA × (URV − LRV). The tool returns results instantly using this formula and the selected parameters.
- What engineering notes should I keep in mind when using 4–20 mA Current Loop Converter?
- NAMUR NE43 defines < 3.6mA as wire break and > 21mA as saturation, which makes instrument diagnostics possible. A 250Ω resistor into a 5V ADC is the simplest front end; its accuracy sets the measurement error, so use 0.1% metal film.