Guide to Avtech Software Sensor Types

Avtech Sensor Types

AVTECH Software have three types of sensors that you can fit to your Room Alert monitor. Each of the different sensor types suit the different purposes that the sensors fulfill.

Digital Sensor

A digital sensor is the most commonly sold sensor for your Room Alert monitors simply because temperature sensors are the sensor most commonly attached to a Room Alert monitor. A digital sensor is able to measure a range of values within a range of values specific to the sensor. A temperature sensor will provide a temperature reading within the quoted temperature range for that sensor type for instance. The connector used on the digital sensors is a RJ-11 connector (see image to left). When a digital sensor is plugged into a Room Alert monitor it is automatically detected by the monitor and data is recorded appropriately. For instance, if a temperature sensor is plugged in then temperature data is logged. If a combined temperature and relative humidity sensor is plugged in then temperature and relative humidity data will be logged.

Switch Sensor

A switch sensor is always in one of two states. It is either in a normal state or an alarm state. A switch sensor is not suited to measuring across a range of values. It is designed to measure when something has gone wrong like a smoke sensor or a water sensor.

There are two main types of switch sensors: Normally Open (NO) and Normally Closed (NC). In simple terms Normally Open and Normally Closed are interpretations of the state of the voltage sent from the sensor to the monitor. A Normally Open sensor keeps voltage on the line when everything is okay i.e. the smoke sensor has not detected smoke or the water sensor has not detected water ingress. A Normally Closed is the opposite. It does not have voltage on the line when the switch is okay. Normally Open is the most common usage given the nature of Room Alert switch sensors. Normally Open is safer from the perspective that failure / disconnection of the sensor will automatically be detected as an alarm condition due to the voltage on the line disappearing.

Analog Sensor

Analog sensors are similar to digital sensors in the sense that they are able to measure from a range of values. The most common analog sensors are the extreme high and low temperature sensors.

Analog sensors are compatible with the Room Alert 12S / 12SR, 12E / 12ER as well as the Room Alert 32S / 32E. Analog sensors can also be fitted to Room Alert 3S / 3E and Room Alert 4E / 4ER by using the analog port on the Digital Temperature & Analog Sensor.

0 – 5VDC analog sensors connect to Room Alert via low-voltage two-wire cable, such as speaker wire.

Analog sensor cable is polarized (+/-).

Monitor Channels

The above photo of a Room Alert 3E is annotated to show the sensor channels. The Digital sensor is marked as an External Environment Sensor Channel and the switch sensor is labeled as a Switch Sensor Contact Set.

The digital sensor is the simplest sensor to attach to the monitor. Simply insert the RJ-11 connector into the connector marked as External Environment Sensor Channel. The digital sensor will then be auto-detected by the monitor.

The switch sensor is slightly more complex. You need to insert the two wires at the end of the switch sensor into the Switch Sensor Contact Set.

[1] You can attach analog sensors like the extreme high and extreme low temperature sensors by using the Temperature & Analog sensor connector attached to a digital port.