node-red-contrib-scale 1.0.0
Node-RED scale node - maps values from one range to another using linear interpolation
node-red-contrib-scale
Node-RED Scale Node - maps values from one range to another using linear interpolation.
Features
- Linear mapping from input range to output range
- Works with inverted ranges (e.g. 100→0)
- Optional clamping to output range
- Runtime overrides via msg properties
- Configurable decimal places (0-10)
Formula
output = (input - inMin) / (inMax - inMin) * (outMax - outMin) + outMin
Examples
0-10 → 0-100:
Input 0 → Output 0
Input 5 → Output 50
Input 10 → Output 100
4-20mA → 0-100%:
Input 4 → Output 0
Input 12 → Output 50
Input 20 → Output 100
Inverted 0-10V → 100-0%:
Input 0 → Output 100
Input 5 → Output 50
Input 10 → Output 0
Configuration
| Property | Description | Default |
|---|---|---|
| Input Min | Lower bound of input range | 0 |
| Input Max | Upper bound of input range | 10 |
| Output Min | Lower bound of output range | 0 |
| Output Max | Upper bound of output range | 100 |
| Clamp | Limit output to range bounds | false |
| Decimals | Number of decimal places | 2 |
Input
msg.payload- Numeric value to scale
Runtime Overrides
| Property | Description |
|---|---|
msg.inMin |
Override input minimum |
msg.inMax |
Override input maximum |
msg.outMin |
Override output minimum |
msg.outMax |
Override output maximum |
Output
{
"payload": 50,
"scale": {
"input": 12,
"output": 50,
"inMin": 4,
"inMax": 20,
"outMin": 0,
"outMax": 100,
"clamped": false,
"decimals": 2
}
}
Use Cases
| Application | Description |
|---|---|
| 4-20mA | Sensor signal to percentage |
| 0-10V | Analog signal to engineering units |
| Inverted | Reverse valve position (100%=closed) |
| Temperature | Celsius to Fahrenheit |
Node Status
- 12 → 50.00 - Scaled value
- 22 → 100.00 (clamped) - Output was clamped
- Invalid range - inMin equals inMax
Author
sr.rpo
License
MIT
