>>Message imported from previous forum - Category:Trio Data Radios<<
User: joelw, originally posted: 2018-10-16 22:00:10 Id:42
This is a re-posting from the obsoleted (October 2018) "Schneider Electric Telemetry & SCADA" forum.
The SmartPath feature in the Trio J Series and K Series unlicensed frequency hopping radios is a powerful tool which can be used to allow a Remote radio to connect to one of many Access Point (Master) radios. This can, for example, be useful to allow mobile robots in a large factory to move between rooms while remaining in communication with the controller, or to provide access to a SCADA system for field operators in their vehicles.
When a Trio system is configured to make use of SmartPath for roaming, two or more Masters are configured to act as sync sources and paths to the SCADA Host for Remote radios. A Remote will connect to the first Access Point it hears and will remain connected until it moves outside the service area of that Access Point.
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Radios equipped with SmartPath are by default configured to remain connected to the current Access Point until that link fails completely, but that can cause intermittent and troublesome connections. An alternate technique is to configure the Remote radios to monitor the receive signal level heard from the Master. If that level drops below a threshold below which the path is no longer considered reliable, the Remote will automatically go looking for another Master with a stronger signal.
Below you'll find a discussion of typical configuration requirements. Only configuration items which are unique to SmartPath will be discussed.
**Configuring a system for Roaming**:
- In ALL radios in the system the network name must be the same.
- In the Remotes you must enter the serial numbers of all of the Access Points into the Trusted Access Points list on the Security Page. (Advanced Unit Setup in K Series)
- When Roaming it is normal to allow a Remote radio to connect to any Access Point. For this, leave the Trusted Access Point Mode set to "Any Access Point."
- If for some reason it were preferred to normally communicate to a specific Access Point, with the others as alternates, the preferred AP's serial number would be entered first in the Trusted Access Points list, and the Trusted Access Point Mode would be set to "Preferred/Alternate."
- By default a Remote will stay connected to an Access Point until total failure of the path. If a cleaner hand-over is desired, enable the RSSI Threshold feature in the Remotes. (bottom item on the Radio config page, or in Advanced Unit Setup in K Series)
- Enter a reasonable Threshold value below which the path is considered to be too weak for reliability, prompting the radio to switch to the alternate Access Point.
- For the 256 kbps speed with its -102 dBm Rx sensitivity the default of -90 dBm is reasonable, though this may be adjusted as desired. In the K Series if set to 32 kbps, the threshold may be set to approximately -96 dBm.
- Other parameters such as hopping speed, radio data rate, serial port configuration etcetera must be set as in any Trio radio system.
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