Many of today’s electronic security systems are designed to operate on a communications/computer network. SDM NetWorkings can help you understand both the intricacies of communication networks, as well as how security systems fit into the networked world. It features excerpts from the “Technician’s Guide to Networking for Security Systems,” a book written by SDM’s contributing technology writer, David Engebretson. (See end of article for ordering information.)

As networks proliferate, security equipment manufacturers have developed IP alarm transmitters. These devices interface with burglar and fire alarm control panels, transmitting alarm, trouble and status reports over the LAN and/or Internet.

Why transmit alarm signals over networks?

One of the primary benefits of IP networked alarm signals is that signals can be received and processed from remote locations, by sending the information over the Internet. By concentrating the monitoring of a number of buildings into a single location, client costs for guards are reduced. Also, IP alarm signals can be monitored at multiple locations, providing an alternative in the event that the primary monitoring station has been disabled.

Another key advantage of IP transmitters is higher security, as the devices can be “polled” by the central station every few minutes for functionality. IP transmitters are approved for use for fire alarm transmission, UL Standard 864, as well as UL Standard 1610 Intrusion Systems, provided that they are properly installed, programmed, and monitored. Using IP alarm transmitters also eliminates issues of trying to connect and communicate alarm signal transmissions over VoIP connections.

At the central station end, supervisory and alarm messages from IP alarm transmitters can be received by a properly equipped alarm receiver, which usually requires a specific line card connected to a broadband Internet connection. As processed by the central station’s alarm monitoring software, there is no difference between the receipt of IP alarm messages and standard digital communications. IP alarm transmitters must be programmed to generate polling messages that confirm remote transmitters’ functionality with the central station on a selectable time basis. UL installations will require a specific maximum time between polling messages.

Pick a Winner

There are a number of issues that alarm installation companies must address to successfully install an IP alarm transmitter at a particular location. The first is product selection – which IP transmitter should be installed?

The alarm industry has become dependent on the telco-connected digital communicator, which can be programmed to provide a wealth of different types of alarm signals, such as user IDs, open/close, system troubles, and specific zone or device alarm activations. An IP alarm transmitter can provide the same depth of information to the central station, provided that it is properly matched for the control/communicator at the client’s location.

The selection of the proper IP transmitter to use is very often dependent upon what specific burglar alarm panel is being connected. Major manufacturers, such as Digital Monitoring Products (DMP), Honeywell Security, Bosch Security Systems, and Digital Security Controls (DSC) provide specific IP transmitter interfaces for their popular products, allowing a relatively simple connection to the panel, and a full range of reporting options.

If no matching IP transmitter is available for a particular panel, the panel can be replaced, or there are other options. An installing company can use a Dialer Capture Module, such as one available from Bosch Security Systems. This device connects to the digital dialer outputs of the panel, and emulates a digital receiver. When an alarm signal is transmitted, the module accepts the digital output, transmits the signal over the IP network to the central station, and simulates the alarm receiver’s acknowledgement messages to the alarm control, after the successful transmission of the IP alarm signal.

If the client’s control panel provides auxiliary voltage triggers or relay outputs, these may be interfaced into IP alarm transmitters that accept those types of inputs. The TL-250 IP transmitter from DSC provides a number of possibilities for connection to existing panels, as well as mating to DSC controls. If the client’s existing control panel only has simple pulse/steady bell outputs, those can be connected and transmitted as separate messages. Controls with separate zone or status outputs also can be interfaced with up to four separate reports (or 12 if the TL-250 is equipped with an expander board).

Receiver Compatibility

Current IP transmitter products will only communicate with receivers manufactured by the same vendor. So the type of central station receiver that will process the signals may well determine selection of a transmitter vendor. If, for example, the central station uses a Bosch/Radionics receiver, Bosch IP alarm transmitters must be used.

Honeywell provides IP alarm transmission capability to participating central stations through the AlarmNet network, which also provides long-range radio and cellular alarm capability. Customers don’t need a radio transmitter at the premises; instead, using a broadband link, they connect to a network access point on the AlarmNet network.

If the IP alarm transmitter is connected to the alarm panel via relay outputs or alarm triggers, the variety and amount of individual alarm messages available for transmission to the central station will be greatly limited, as compared to standard digital alarm signals. Detailed signals such as individual zone alarms, user-specific open/close reports, and other such expansive alarm and supervisory signals may be impossible to pass to the IP alarm transmitter.

Installing IP Alarm Transmitter

There are several issues to consider when installing an IP alarm transmitter. The first is the data connection to the network. A network connection, typically a UTP Cat 5e or higher quality, must be available to connect the IP transmitter, located in or near the alarm control panel, to an available port in the IP network. This may be an otherwise unused RJ-45 jack on the wall, or new UTP cable may need to be run to bring the network to the alarm control. It’s possible that the alarm panel may be installed within the main cross-connection or horizontal cross-connection room, making connection to the network a simple process.

Once the IP transmitter is in place, it must be programmed to the proper central station ID, as well as other selectable features. Programming methods will vary with different manufacturers, as well as the particular central station receiver being used. Although a particular IP transmitter may be programmable over the network, use of a laptop computer will provide the technician with a quick connection to the transmitter, as well as easy viewing of the transmitter’s indicating LED array.

Along with programming the IP alarm transmitter, the control panel outputs may need to be turned on via a keypad or programming selection, and the central station receiver must be programmed to receive alarm signals and supervisory messages from the field device.

Digital Dialer Backup

While IP alarm transmitters provide much higher security than telco-connected digital communicators, connecting a telephone line to the digital communicator outputs of a control panel can provide dual and/or backup reporting. This would be desirable in the event of IP transmitter or network failure. Client or telephone network use of VoIP (Voice over Internet Protocol) may negate this feature, as some digital formats will not pass through this digitized voice protocol, and a VoIP connection often becomes inoperable when the computer network goes down.

The vital technology of remote downloading of control panel functions can be affected by the installation of IP alarm transmitters. If the IP network is the only communication connection to a particular panel, telco-based downloading will not be available for that system. Some vendors, such as DSC, provide for remote downloading capability over the Internet by using a specific software set in the downloading computer.

Some transmitters can be programmed to transmit alarm signals to multiple IP-addressed receivers, providing redundant or backup transmissions. This is a powerful feature, as critical alarm messages can be transmitted to a traditional central station, while supervisory or less important transmissions (along with critical burg/fire messages) can be received and responded to by the client’s own monitoring facility.

Signal Encryption & Security

With the ready availability of literally millions of Internet connections, alarm equipment vendors have built sophisticated signal encryption into IP alarm transmitters and receivers. Signal encryption defends against a rogue transmitter being used to emulate “I’m OK, no alarm signals here” polling signals emanating from an IP alarm transmitter at a target installation. Typical encryption programs used are Blowfish, which uses a 1024-bit format, and 128- and 256-bit AES.

Quick Tip: IP Addressing

Network devices must each have a unique IP address to allow them to communicate with other devices on the local network, and access the Internet. (For more information about IP addressing, see “How to Manage IP Addressing,” SDM April 2005, p. 74.)

Quick Tip: Testing Alarm Transmissions

As with any type of alarm signal transmission technology, complete and thorough testing of all alarm signals to the central station should be performed by the installer before completing the installation and leaving the job site.