Information on sensor types used in environmental monitoring systems for a range of room and building applications.
Digital sensors and Analog sensors are two types of sensor that can be used in environment monitoring. A digital sensor monitor a state, being ‘On’ or ‘Off’ i.e. 1 or 0. An Analog sensor monitors provides a continuous or intermittent (sampled) data stream for analysis. Example of an analog sensor is a temperature or temperature/humidity sensor. An example of a digital sensor would be Power Sensor which is signalling whether a power supply is on or not. A typical analog data sensor is a temperature probe.
Analog sensors measure a range of values and the most commonly used analog sensor is one that monitors for temperature ranges from low to high or extreme temperatures. Analog sensors connect to the analog port on an environment monitor.
The term digital sensor is generally applied in engineering to a device that monitors a binary output i.e. 1 or 0, ON or Off. The term ‘digital sensor’ in environment monitoring can also refer to an ‘intelligent’ sensor that monitors data within a range of specific values. This term is commonly used with Avtech Room Alert devices. Avtech digital sensors include temperature and temperature/humidity monitoring sensors. When either of these are plugged into a compatible environment monitor, the temperature or temperature/humidity data is automatically logged for analysis.
A switch sensor uses relays that are either Normally Open (NO) or Normally Closed (NC) and can only be on one of these two states. The states can be used to indicate normal running and alarm conditions. When the set condition being monitored changes, the switch sensor changes from NO to NC or NC to NO. The opening or closing of the relay determines whether a voltage is present and it is this that an environment monitoring device monitors and records or uses to invoke an action in a detector i.e. a Smoke Alarm, Air Flow, Fuel Tank level or Water level monitor.
An actuator is a device that responds to a digital input or output and moves. It is a control mechanism for a system that responds to a signal to indicate the need for a change in state such as a valve to open or circuit breaker to be opened.
A 1-Wire sensor is a sensor using the 1-Wire device communications bus. This provides a low-speed data signal and power using a single conductor. 1-Wire is typically used to communicate with small devices like digital thermometers and measurement devices. When a 1-Wire sensor is connected to an environment monitor, the system can be termed a ‘MicroLAN’. The term ‘1-Wire UNI’ is used to refer to sensors other than for temperature or humidity.