Overview - Qolsys S-Line Encryption

In this video, Jorge from Alarm Grid talks about the Qolsys S-Line Sensors. The sensors utilize rolling code encryption when paired with a Qolsys IQ Panel 2 or a Qolsys IQ Panel 2 Plus with 319.5 MHz Daughtercard. When used with a different 319.5 MHz system, the S-Line sensors do not use encryption.

Qolsys S-Line Sensors are 319.5 MHz devices that utilize rolling code encryption when enrolled with a compatible IQ Panel 2 or IQ Panel 2 Plus. When an S-Line sensor is enrolled with one of these panels, it will engage in two-way communication with the system's transceiver. Faulting the sensor will tell it to send an encrypted transmission to the transceiver. These transmissions always occur at 319.5 MHz, but they are encrypted so that only the panel will know the next coding in the communication sequence. In order for any command to go through successfully, the panel must respond to the sensor with the secret encrypted code. Once the sensor receives the successful return signal with the proper encrypted coding, the sensor then "rolls" onto a new encrypted code for the next interaction. Again, only the panel will know this new encrypted code.

However, Qolsys S-Line Sensors only use this rolling code encryption when they are used with a Qolsys IQ Panel 2 or compatible IQ Panel 2 Plus. These sensors are smart enough to detect which type of system they are paired with upon enrollment. If you use a Qolsys S-Line Sensor with a different system, such as an Interlogix Simon Series Panel or an original Qolsys IQ Panel, then the sensor will just operate as a non-encrypted 319.5 MHz sensor. This is what allows these sensors to be backwards compatible with older 319.5 MHz systems. But when you use these devices with one of the systems that support S-Line encryption, then they will operate as bi-directional sensors to take advantage of the benefits of encryption. The S-Line rolling code encryption makes it nearly impossible to take over these devices or to trick or manipulate the system using special hardware.https://www.alarmgrid.com/faq/how-does-qolsys-s-line-encryption-work

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