Issue
Online Device shows "0" for one scan, but the device is still online from TAC Vista. This is enough for the unit to stop and close dampers.
Product Line
TAC Vista
Environment
- Vista Server
- Xenta 281
- Xenta 301
- Xenta 401
Cause
The Online Device function depends on your network.
If two controllers are within the same TAC Xenta group, there should be no extra traffic the asking device could just check in the online table if the other device has sent out its poll lately.
If it is outside the actual TAC Xenta group, it will be like a TACNV connection, within the limits for TACNV. However, there are no re-sends. A single missed message will result in an Offline status.
If there is a lot of traffic, there could be a collision on the network traffic and this could result in an Offline status. The next scan time, the messages might work correctly again, and resulting in online status.
Resolution
The best solution is to have a Delay block in the TAC Menta code, to get a delay-off (when the value goes from Online (1) to Offline (0)). Make sure the device is offline for at least a few program cycles before taking any action in the application program logic.
