Issue
Needs to know how often Vista (or Xenta Servers) do online/offline polls for Modbus and MBus devices
Product Line
TAC Vista
Environment
- Xenta Server
- Modbus
- Mbus
Cause
The devices may go offline for several different reasons. It's not possible to give a precise answer to this question, since it depends on your setup and the number of devices.
Resolution
In general, if a Modbus device has been detected as offline by the Xenta Server, it will wait 60 seconds until it tries polling that device again. That doesn't mean that a device will come online after 60 seconds if it has been offline because as described below, other factors comes into play, such as the number of devices and registers, and invalid registers.
Mbus:
The Mbus protocol is designed so that all information in the device will be received at every poll, regardless of what is defined in the device template. If the Xenta Server doesn't receive any information it will retry twice and if still no reply it will set the device to offline.
All offline devices will be transferred to an offline queue in the Xenta Server, and at every new poll one device (the oldest) will be moved to the poll queue again.
The reason for not retrying all is that if you have lots of devices that are offline at the same time, each poll would take very long time to complete and if using a short poll interval it may not be finished in time before the next poll. That will also mean that if you have many offline devices and have set a long poll interval in Xbuilder (default 1 min) it may take quite a while until all devices are online again.
Note: In Xbuilder 5.1.9 and later it's possible to set the number of offline devices to poll each cycle. In some cases, for example when there are few meters and/or long poll times you may want to increase this number.
Modbus/TCP:
You will have a Server address for the TCP Client and if that server's ip address can't be reached all the Modbus devices below it will go offline. However as soon it can be reached again (will be tried constantly), it will scan all devices below it, and if they reply they will be set to online.
If there's no response from a single device, it will retry twice before it's set to offline. The time it will take depends on the slave timeout setting in Xbuilder (default 3 seconds). As for Mbus, you have an offline queue where 1 device will be moved to the poll queue every poll cycle. The total poll time also depends on how many devices and registers you have defined (many devices/registers = longer poll time = longer time to detect if a device is offline/online).
Modbus/RTU:
It works similar to Modbus IP, except for the server part (which is not present).
Besides that, you also have the "transmit delay" setting in Xbuilder (default 0 ms, max 1000 ms) which may effect the time it takes for a device to be reported as online/offline
