When you click in the Bacnet Device Manager, a Configure Device Discovery dialog appears, as shown in Figure 22.
Starting in AX-3.7, buttons and were added for the Networks field. These can be useful in some cases to limit a device discover to certain BACnet networks.
Depending on the size of the BACnet internetwork you are learning, you may wish to configure settings from defaults. By default, all known networks are selected to learn (each network number matches an entry in the router table), “Send Global” (or “All Networks”) is not selected, and the full range of device IDs (0 to 4194302) is specified.
Fields in the Configure Device Discovery dialog work as follows:
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Device Low Limit
Devices with an instance ID lower than this are not discovered. Default value is 0.
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Device High Limit
Devices with an instance ID higher than this are not discovered. Default value is 4194302 (the maximum valid BACnet device instance number).
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Networks
Allows selection of either:
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Send Global? (All Networks) — Niagara will search on all possible BACnet networks segments, including all locally connected networks, as well as segments accessed over BACnet routers.
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<Known networks (by network number)>— Choices reflect the number of network ports available under Bacnet Comm, Network component, plus any additional remote networks discovered by receiving “I-am-router” messages. Click to include/exclude as needed. By default, all known networks are individually pre-selected.
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Wait Response Time
Determines how many seconds Niagara waits before determining that all BACnet devices that exist have responded to the discovery request. The default value is 10 seconds.
Often, you may wish to further limit the range of device IDs, or perhaps enable the device learn globally (“Send Global?” or “All Networks”). In the case of MSTP networks, or complex BACnet networks (that span several routers, you may need to set the “Wait Response Time” upwards (from 10 seconds) in order to learn all BACnet Device objects.