4RF Aprisa SR+ User Manual - page 89
86 | Managing the Radio
Aprisa SR User Manual
LISTEN BEFORE SEND
When the Access Mode is set for Listen Before Send, the Listen Before Send parameters can be set:
Network Type
This parameter sets the operating mechanism used in the FAN:
Network Type
Function
Polled
The SR radio network is part of a polling system e.g. if a SCADA
master station is set up to periodically poll remote terminal units
(RTUs).
Channel access for data traffic in this case is completely controlled
by the external SCADA master.
Exception
The Base Station and all remote and Repeater Stations can send
traffic asynchronously.
The default setting is Polled.
All Channel Access parameters are calculated and set automatically for the network topology and the size
of packet that is being transmitted. This improves channel utilization if there are variable size packets on
the network.
When the Network Type is set for Exception, the Access Rate and Network Size parameters can be set:
Access Rate
This parameter defines the rate at which the channel is accessed by remote or Repeater Stations. It is an
approximation of the traffic rates on the FAN.
The default setting is 1 per min.