No Busmonitor modus
Dear gentlemen,
* ETS does not use its RS232 device is Busmonitor mode when programming the Physical Address of a remote device.
- It needs to send out the request, and sending is not possible in Busmonitor mode.
- It does also not switch back to Busmonitor Mode for receiving the answer, as this is not necessary (Broadcast messages are received also in normal Link Layer Mode) and takes that much time for the BCU that the response from the remote device would not be noted.
So, ETS is in Normal Operation mode of the Data Link Layer.
* ETS also properly acknowledges the messages.
Actually, it is the RS232 device that does this. So, NACK's or BUSY's can only be due to the RS232 device, not due to the ETS.
But ... in the cases we have analysed ... ETS gets the repetitions... (see (!) below) An RS232 device will not pass the messages up in its message stack if it has sent NACK or BUSY.
So, also the RS232 device does not cause the BUSY or NACK.
* The cases we have analysed all show BUSY acknowledges to both the request (by ETS) as the response (by the device with the pressed programming button). So, some ... )&ç!'( ... device is sending BUSY. This causes the repetition of the response by the answering device, but also of the request by ETS. This is fully in line with the EIB specifications.
=> Find the BUSY sending device (decouple one after the other from the bus).
(!) The NETTO effect is that ETS gets multiple answers on its read request. But ETS shall not program the physical address when more than one device is in programming mode. So, ETS brings this message...
Some aspects:
- All answers come from the same device. ETS can detect this.
- All answers indicate Link Layer repetitions. ETS can detect this.
==> The rule for ETS could thus be to ignore multiple answers from the same remote physical address if all or all-but-one have the repeat flag set.
This could be a solution.
Please note however: devices that have not been programmed yet (have been unloaded) all have the same physical address. if when trying to program these, more than one such device is in programming mode and there are Link Layer repetitions, ETS will - according the above rule - ignore this and set the same physical address to all devices.
This is one solution, based on the assumption that the above is quite unlikely.
Another solution would be to change the error message from "More than one device in programming mode" to "ETS received multiple identical responses when searching for devices in programming mode. There may be more than one device in programming mode, or the request cycle has been corrupted." "Continue Yes/No"
Under discussion.
Drs. EIB
Mr. Steven De Bruyne
System Department - KNX Association
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