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Connection Monitoring Overview

This section explains how evalink talos controls the state of the connection with an alarm transmitter device (alarm panel), to make sure that the device is operational and capable of sending alarms.

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The term supervision, though using actively in the industry and mentioned in evalink talos UI, is not used in this documentation.

The following terms are used instead:

  • supervision in its generic meaning (controlling the connection) – connection monitoring
  • supervision interval (the time interval after which CID 350 or its analog, CID 351, or CID 352 alarms are reported) – the reporting time control interval. For details, see section Control Intervals

Polling​

The connection between the virtual receiver and the transmitter is verified by means of polling – the exchange of keepalive messages and responses to those between the transmitter and the virtual receiver.

Connection monitoring is a procedure according to which a virtual receiver checks the polling frequency via a series of control intervals and performs the appropriate actions. Examples of such actions are:

  • if no polling occurs during a control interval known as site reporting time – signals that a transmitter is disconnected by reporting a CID 350 alarm or its analog

  • once polling is received again after a failure – reports a CID 350 alarm restore and restarts counting the appropriate control intervals

    For a definition of a polling interval, see section Control Intervals in this article.

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Whenever a transmitter is connected or reconnected to evalink talos, a connection restore alarm or a series of such alarms (depending on the virtual receiver configuration) are generated for a site.

Connection Monitoring Schemes​

Direct Connection Monitoring​

The major part of virtual receivers in evalink talos use the direct connection monitoring scheme, in which:

  • the virtual receiver and the transmitter

  • the keepalive messages exchanged between the virtual receiver and the transmitter are native device heartbeat / ping messages and responses to those

  • a virtual receiver in evalink talos controls not only the reporting times for the paths and for the whole site, but sometimes also the polling intervals for the transmission paths (see section Control Intervals in this article)

The generic connection model for this scheme is shown on the figure below.

Direct_(SLA)_connection_monitoring_scheme

This connection monitoring scheme is also known as SLA scheme, since the control intervals for this scheme are set by selecting an appropriate Service Level Agreement (SLA) option in the virtual receiver settings. See section Direct Connection Monitoring (SLA) > Set SLA for a Virtual Receiver for details.

Indirect Connection Monitoring​

In the indirect connection monitoring scheme:

  • a virtual receiver is connected to a third-part service, not to the transmitter directly. The third-party service is connected to many transmitters at once

    An example of a third-party service is the Frontel GI server that comunicates with the Virtual Frontel GI Receiver in evalink talos.

  • the keepalive messages that evalink talos receives from the transmitter are higher-level polling alarms. There alarms are generated by the transmitter, and are then forwarded by the third-party service to evalink talos

  • there's no concept of a transmission path, since there's no direct connection to the transmitter – therefore, polling intervals and path reporting times are not controlled

    The virtual receiver controls only the site reporting time (see section Site Reporting Time in this article).

The generic connection model for these virtual receivers is shown on the figure below.

Indirect_connection_monitoring_scheme

This connection monitoring scheme is used by:

  • Sur-Gard based virtual receivers – Generic Surgard Receiver, Farwest IP Receiver, Farwest VoIP Receiver
  • Virtual Frontel GI Receiver

For a list of integrations that rely on these receivers, see section evalink talos Virtual Receivers.

coming soon

Configuring control intervals and other settings for Sur-Gard based virtual receivers and Virtual Frontel GI Receiver will be described in the next documentation releases.

Control Intervals​

The following control intervals can be monitored by a virtual receiver, depending on the connection monitoring scheme:

Site Reporting Time​

A site reporting time is a control interval, after which, if no polling arrives from a transmitter on any of the transmission paths, evalink talos reports the site failure – an alarm with a CID code 350 or its analog in other alarm protocols.

The site reporting time value for a particular virtual receiver is set on evalink talos side and is fully controlled by evalink talos.

Site Reporting Time Length​

The site reporting time should be set to a reasonable value that allows to avoid sending unnecessary alarms.

At the same time, if the transmitter needs to be certified / comply with security standards, the site reporting time must be set equal to the appropriate maximum value specified in the concerned standard.

tip

For example, transmitters that conform to the EN 50136-1:2012 standard and need to qualify for the DP3 category, must have site reporting time set to 4 minutes – the maximum reporting time for Failure of all ATPs at the same time, see section EN 50136-1:2012 Standard and Swiss Requirements for details.

Factors that Affect Control Interval Values​

Security Regulations​

If the transmitter if the transmitter needs to be certified / comply with security standards, the site reporting time (as stated above) and the path reporting times must be aligned with the maximum reporting times that the regulatory standard defines for the appropriate category. See the TIP in section Site Reporting Time Length for an example.

The predefined reporting times that evalink talos offers are based on the values provided in section EN 50136-1:2012 Standard and Swiss Requirements.

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The category that a transmitter must qualify for often depends on the sensor / alarm panel type. For example, in Switzerland, a short reporting time is required for fire panels – the typical choice for this type of panels would be DP4 / SP4 category. For intrusion panels, DP3/SP3 category suffices in most cases.

The length of the polling intervals set for each transmission path is also affected by the regulatory requirements. The polling intervals configured for a path must be short enough to ensure early detection and, therefore, timely reporting of the connectivity issues.

The transmitter and the virtual receiver communicate over IP protocol. On top of that, some transmitters use TCP, while others use UDP protocol for communication. For the protocols used by the particular virtual receiver, see section evalink talos Virtual Receivers.

A transmitter that communicates over TCP can be configured to have a permanent TCP connection with the virtual receiver or to connect when necessary and then disconnect, the decision is up to the user in most cases.

evalink talos is configured to close a TCP connection if no polling is received for 340 seconds. Therefore, when the transmitter is set up to use a permanent TCP connection, set the polling interval on the concerned path to 300 seconds (the recommended safe value).

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