DSC Sur-Gard SG SYSTEM III Central Station Receiver

The DSC Sur-Gard SG System III is a multi-line, rack-mounted central station alarm receiver made to keep an eye on a lot of fire and burglary alarm panels in professional central monitoring stations. It takes in alarm, trouble, and test signals via phone and IP communicators, adds a time stamp to each occurrence, and sends the information to automation systems, printers, and local displays so that operators can take action. ​

System Function and Capacity

The SG-System III is a Class 1, fixed, rack-mounted receiver that can hold several SG-DRL3/SG-DRL3-2L telephone line cards and SG-DRL3-IP IP line cards. A completely set up system can usually accommodate up to 24 line cards per receiver. These line cards can work with both dial-up phone lines and IP communication channels. Each line card can monitor several alarm accounts using up to 64 pre-programmed forms (profiles) per card.

The receiver adds time and date stamps to all incoming alarm data. It can send events to central station automation by TCP/IP or RS-232, to a printer that is nearby or far away, and to the front-panel LCD display so the operator can see them.

Types and Aspects of Communication

Each SG-DRL3 family line card can send alarms in a number of various ways, like Contact ID and SIA. You can also program it with a lot of different handshakes for each profile to make sure it works with a lot of different control panels. The System III has patented features like automatic handshake selection (AHS), caller ID, ANI/DNIS reception, and advanced two-way audio integration.

These features help central stations identify callers, choose the right format, and support audio verification when used with compatible field devices. The system can also make and record test signals between receivers in the same monitoring center and transmit test messages to check that the communication pathways are working. ​

Redundancy and Hardware Architecture

The SG-SYSTEM III is a modular 19-inch rack system with hot-swappable cards. This means that you may change out line cards, CPUs, and power supply modules without turning down the system or losing receiver capacity. Each rack can store up to 12 line cards and their modules.

Configurations can include extra receivers and power supplies for high availability, with automatic switching redundancy and continuous connection supervision (heartbeat) between the receiver and the central automation servers. Each line card has non-volatile memory that keeps configuration data and event buffers (usually hundreds of events per card) so that alarms stay on even if the power goes off.

Information about the electrical and installation

The SG-System III usually gets its power from a universal AC input of around 110–240 VAC, 50/60 Hz, with a maximum input current of about 2.5 A and a power usage of about 25 W per rack. It is also sometimes backed up by an external UPS for standby operation.

It is classified as plug-in, stationary equipment that must be securely fixed in a rack and installed in accordance with electrical codes and relevant UL/ULC standards such as UL 1610 (Central Station Burglar Alarm Units), UL 864 (Fire Alarm Systems), UL 827 and CAN/ULC‑S304/S561 depending on the application and region.

The front panel has a quarter-VGA or big LCD screen and navigation buttons for programming and checking the status locally. The back panel has connectors for a parallel printer, numerous RS-232 serial ports, and 10/100Base-T Ethernet for automation and remote setup. ​

Supervision, monitoring, and approvals

The receiver keeps an eye on phone lines and IP links all the time, logging and reporting line failures, network problems, and disconnects to the LCD, printer, and automation software so that operators may respond promptly.

When used with appropriate DSC/T-Link communicators, it can handle static IP addressing and encrypted IP communications. It can also work in a data network polling environment that meets strict 90-second supervision requirements for some ULC applications.

The SG-SYSTEM III is listed and approved for use as central station receiving equipment in both fire and burglary alarm monitoring. It meets CE EMC and low-voltage directives as well as North American listing standards. This makes it a good choice for professional monitoring centers that need a lot of capacity, redundancy, and compliance with the law.