What is a Dry Contact?
A dry contact output can also be referred to as a volt-free contact, relay, or contact output. It is nothing more that a stand-alone set of two contacts with no voltage, current, or anything else impressed across the contact set. A dry contact essentially looks like an electrical switch. There are two states for a dry contact: open and closed. On a normally open dry contact output, when the switch is open, the device is in a normal state. When it is closed, the device is in an alarm state. In a normally closed dry contact output, it is the opposite.
Devices That Use Them
Dry contacts are most commonly used as outputs for sensors. There are many useful sensors with dry contact outputs on the market. Applications vary from smoke detection and carbon dioxide detection, to motion detection and water detection. Any sensor with two states, alarm and no alarm, can have a dry contact output. However, a dry contact by itself is not very useful. Something needs to take that dry contact output and react to the status of the sensor.
The Internet of Things has revolutionized the ability to get the status of anything from anywhere. Once that sensor output is in the cloud, the sensor can be monitored from anywhere, and notifications can even be received when something goes awry. This requires a cloud service and a cloud connected dry contact receiver such as the ConnectSense Dry Contact Sensor.
With a cloud service for a dry contact sensor, like the one at ConnectSense.com, the device can be accessed by logging into an account on a webpage. From there, rules can be set up on what to do when the status of the dry contact is open or closed; e.g., If dry contact 1 is open Then text me And Trigger my ConnectSense Siren/Strobe Sensor. This can be done in a web browser from anywhere in the world.
With a cloud-based solution for a dry contact sensor, one can receive text messages, phone calls, and emails, send tweets, and even trigger other output devices like power relays and siren/strobes. Utilizing a cloud based Dry Contact Sensor gives home owners and business owners peace of mind because they can check in and also be notified while away from the environment they are monitoring.