Function | LED display
RF/TP media coupler/repeater | Order no. 5110 00 | 51103300
Page 27 of 42
On a KNX RF, in addition to the physical and domain addresses of the transmitter, a
telegram is also given an LFN (Line layer Frame Number). This LFN is a 3-bit coun-
ted measurand (value 0...7) which, starting at "0" for each new telegram, is counted
up with value overrun by "1" by each transmitter (example, hand-held transmitter:
press ON button -> LFN = 0, press ON button again -> LFN = 1, press OFF button ->
LFN = 2 etc.). Repeaters do not change the LFN value when repeating telegrams.
In addition, an RF telegram is also given a telegram repeat counter (similar to the
routing counter for a TP telegram / also"RF repeat counter"). When a transmitter
sends a new telegram for the first time, it is given the repeat value "6". As soon as a
repeater receives this telegram and forwards it, the value is reduced by "1". For each
additional repetition process via another repeater in the same RF domain, the repeat
value is again reduced by "1". Once the value is "0", the telegram is no longer re-
peated. With this process, an RF telegram can be forwarded through a maximum 6
repeaters in one domain. Only repeaters are permitted to influence the telegram re-
peat counter.
Because the last received telegrams and the evaluations of the LFN and the tele-
gram repeat counter for newly received telegrams are saved internally, media
couplers and all other RF devices can recognize whether a telegram has already
been received and processed or not, despite of its identical user data content. This
internal saving also permits repeaters to recognize whether they themselves have
already forwarded the received telegram and therefore do not need to do so again.
The domain address of an RF telegram and the LFN can be displayed in ETS
group or bus monitors under "Medium Info".
8.3
LED display
The device has a two-colour status LED. This LED displays device statuses in normal
operation and during commissioning or maintenance.
The following display functions have been implemented:
–
LED lights red:
Programming mode is active. Programming mode is activated by pressing the
programming button or by using the ETS. Programming mode is deactivated
after the physical address has been successfully programmed, or is generally
deactivated by a device test (power failure, ETS programming process of the
application program). Programming mode is also deactivated automatically
after 4 minutes if none of the above events occurs.
–
LED flashes slowly red:
Safe-state mode is active (see chapter "Safe-state mode"
–
LED flashes red quickly (only in operation as media/segment coupler):
Filter function has not been configured (filter table has no function). This dis-
play is dependent on the parameter settings of the coupler. If the parameter
"Telegrams TP -> RF group telegrams" and/or "Telegrams RF -> TP group
telegrams" is configured to "forward unfiltered" and the device is started up
with this parameter setting, the status LED flashes red quickly. This is a sign
that the filter table has no function.