Analogue Sensors
Analogue sensors are used to monitor a wide range of physical measurements — temperature, pressure, humidity, CO₂, and more. This guide explains how these sensors work and what to check if your readings appear incorrect.
How Analogue Sensors Work
An analogue sensor outputs an electrical signal that varies continuously with the physical measurement it is monitoring. The most common signal types are:
- 4–20mA current loop — widely used for industrial sensors.
- 0–5V voltage output — common for environmental sensors.
The transmitter reads this signal and converts it into the measurement you see in Live. To do this correctly, the system needs to know both the signal range and the corresponding measurement range — for example, that 4mA corresponds to 0°C and 20mA corresponds to 100°C.
Think of it like a ruler: the signal is the ruler, and the measurement range tells the system what the marks on the ruler mean. If the ruler is miscalibrated, every reading will be wrong by the same factor.
Common Issues
Readings are wrong by a consistent factor (e.g. 10 times too high or too low)
This is almost always a configuration issue — the measurement range set in the system does not match the sensor's actual range. For example, if a sensor measures 0–1000 Pa but the system is configured for 0–100 Pa, every reading will appear ten times higher than it actually is.
Contact support with your sensor's datasheet or model number so we can verify and correct the configuration.
Readings are in a strange unit or do not match the physical measurement
The sensor setup in Live may be configured for a different sensor type. Contact support with details of the sensor you have installed and we can update the configuration.
Readings appear correct at some values but not others
This can indicate a wiring issue or a sensor that is beginning to fail. Check that:
- The sensor cable is undamaged and securely connected at both ends.
- The sensor is positioned correctly in the environment it is monitoring.
- There are no signs of physical damage to the sensor.
If the wiring and positioning look correct, contact support — a replacement sensor may be needed.
Readings are always at the minimum or maximum value
A reading stuck at 0 or the minimum value often indicates a broken or disconnected wire. A reading stuck at the maximum value can indicate a short circuit or a faulty sensor. Check the cable connections at the sensor and at the transmitter. If connections look fine, contact support.
At Installation — What to Check
If your sensor has recently been installed and readings do not look right, please ask the installing engineer to verify:
- The signal type is set correctly (4–20mA or 0–5V).
- The minimum and maximum measurement values match the sensor's specification.
- The sensor is reading the correct value when tested against a known condition.
Getting this right at installation prevents data quality issues further down the line.
When to Contact Support
- Readings appear incorrect and you are not sure why.
- You need to change the sensor type or measurement range in the system.
- A sensor has been replaced and you need the configuration updated.
- Readings are stuck at a fixed value.