User's Manual

ManualsBrandsWürth Elektronik ManualsElectronicsDigital transmission module

13.1 Setup of the network and repeater device

The repeater mode can be enabled with setting Bit 0 accordingly in the

RpFlags

As ACKs are not supported by the repeater mode all network members must

make sure that the UserSettings value of

MAC_NumRetrys

is set to 0.

If the module is conﬁgured as repeater, the following notes have to be considered:

1. Requirements on the network:

a) The repeater devices have to be line-powered (no battery), since due to packet

repetition it demands more energy.

b) Depending on the data rate, each repeater should repeat a maximum of 2-5 pack-

ets per second to give a good chance that the repeater is not busy with repeating

when already a new packet arrives for repetition. Otherwise, packets can get lost.

Please setup your network such that this requirement is fulﬁlled. More packets

per second will result in more packet loss as the collision probability is increased.

c) If the network consists of several layers of repeaters, each layer delays the packet

transmission additionally.

d) To setup the network all participants have to use the same

RADIO_DefaultRfProfile

RADIO_DefaultRfChannel

and

MAC_DefaultAddressMode

e) The network must be designed by the user in a way the duty-cycle requirements

of the local regulatory requirements cannot be exceeded.

2. Information for the repeater device:

a) Acknowledgements (ACK) of successfully received packets are blocked. If an

ACK is requested by the sending module, the request is ignored. Furthermore,

the repeater does not request any ACK, when repeating a packet.

b) The "packet sniffer" mode cannot run at the same time as the module is in repeater

mode.

c) Each time a packet has been repeated a

CMD_REPEAT_IND

is output over UART.

Depending on the address mode, the address of the involved devices is placed in

the

CMD_REPEAT_IND

telegram. With this the original sender of the RF packet and

the device, that is supposed to receive the packet, can be identiﬁed.

3. Information for the sending and receiving devices:

a) The senders should send less frequently to avoid packet collision on the frequency

channel and to not exceed the duty cycle requirements.

b) The repeater devices do not support the feature of ACKs for the successful re-

ception of the packets. Thus, the sender will never receive ACKs if requested.

To ensure that transmitted packets are successfully received by the destination

device, the network administrator has to integrate his own acknowledging feature

in the customer’s application. To be sure that the sender does not request ACKs

the UserSetting

MAC_NumRetrys

must be set to 0.