Update Interval (Command Heartbeat) - Johnson Controls - LIT-1201668 - System Integration - LonWorks Integration - 12.0

LonWorks Network Integration with Network Engines and LCS Technical Bulletin

Johnson Controls
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LonWorks Integration
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Technical Bulletin
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The Update Interval attribute (Figure 1) is provided for every LonWorks output point object. This attribute enables a recurring heartbeat message from the network engine to controllers that require periodic contact. If a heartbeat message is not present, some LonWorks devices revert to local control.

Update Interval takes an integer value in seconds. The default is 0 seconds, which disables the heartbeat. The network engine can issue one heartbeat per second (maximum).

Note: To prevent excessive traffic over the network, we recommend that you use an interval between 2 and 5 minutes (120 to 300 seconds), and enable the interval for no more than two objects per LonWorks device. Use this capability sparingly. You may configure an update interval of 1 minute, but if you do so, decrease the number of points on the network that use this attribute. For example, if you configure over 60 objects at 1-minute update intervals each, the network engine cannot issue updates to all of them within that minute, which causes delayed updates.

Once you enable the Update Interval, you must activate it by commanding the point to a different value or state, restarting the network engine, or taking the LonWorks device offline temporarily. You should also make sure the point is set for Auto Restore by assigning a value of True. Auto Restore restores the last command on the field device when the point returns from an offline condition, or when it is first starting up.

Figure 1. Update interval attribute