Frequently Asked Questions

This section addresses problems you might encounter when setting up and operating the KNX driver:

• Why does it take so long for my KNX IP router to come online?

  At startup, a read request is issued for each group address to initially populate the cache. Ideally, the IP router should come online as soon as a response has been received back from each group address.

  However, there is no way for Plant SCADA to determine if a read request has been lost due to an unreliable destination address.

  Under these circumstances, you would like any valid addresses to be acknowledged, and for communication to commence. The lost addresses should not hold up communication with the rest of the system.

  For this reason, the KNX driver has a initialization timeout period set to 120 seconds. After this period of time, all validated group addresses (a minimum of at least one) will commence communicating; all invalid addresses will be terminated with an error written to the driver log.

  Therefore, if your IP router is taking a couple of minutes to come online, it probably means invalid group addresses are forcing the device to the end of the initialization timeout period. You should check the driver log to determine which addresses are causing the problem.

• Everything is plugged in to the network, but I can't see any packets from Plant SCADA in the bus monitor.

  If this is occurring, check the following:

  • If you have multiple network cards (or virtual NICs just from having VMWare installed) you need to confirm that the parameter [KNX]LocalIPAddress is set to the correct out bound interface.

  • Confirm that the routers are configured correctly to route messages to and from the KNX network.

  • Confirm that all group addresses are configured as readable.

• When I try to write to a group address, the new value flickers and then reverts to the old address.

  Confirm that the group address is configured to be writable.

• Unicast mode communication to the KNX network not established. Unit status is offline and all tags show BAD quality

  Make sure the Router is configured for Unicast communication mode. Also check that special option field of port form is configured with the IP address and Unicast port of the router.