Router - Base Driven, Detail Description; Router - Base Driven, Functionality Example - RACOM RipEX User Manual

RipEX in detail

2.3.5. Router - Base driven, Detail description

All traffic over the Radio channel is managed by the Base station. Radio channel access is granted by
a deterministic algorithm resulting in collision free operation regardless of the network load. Uniform
distribution of Radio channel capacity among all Remotes creates stable response times with minimum
jitter in the network.
All communication on Radio channel is controlled by the Base station; all frames inside the radio network
have to be routed through the Base station. Appropriate routing has to be set.
Base station can communicate with different Modulation data speeds and different FEC settings.
Any Remote can work as a Repeater for another Remote. Only one Repeater is possible between Base
station and Remote, however a number of Remotes can use the same Repeater.
There is no need to set any routes in Routing table(s) for Remote stations located behind Repeater.
Forwarding of frames from the Base station over the Repeater in either direction is serviced transparently
by the Base driven protocol.
When Remote to Remote communication is required, respective routes via the Base station must be
set in Routing tables in the Remotes.
Frame acknowledgement, retransmissions and CRC check, guarantee data delivery and integrity even
under harsh interference conditions on the Radio channel.

2.3.6. Router - Base driven, Functionality example

A star topology with one repeater is used in the following example of a SCADA network using a polling
and report by exception combination. The Repeater is also serving as a Remote radio. The packets'
acknowledgement on Radio channel is used for transmissions in both directions in the example
Fig. 2.4: Router - Base driven, Functionality example
sends the reply to Remote RipEX1. During the checking process the Base RipEX detects a prepared
packet in the queue of RipEX1 and subsequently allots a Radio channel for transmission of the packet.
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Step 1
Base RipEX regularly checks the
queue status of remote RipEX
radios for which it has no
queueing information. The feed-
back enables the Base station to
manage time allocations for all
Remotes to transmit.
Step 2
FEP sends a request packet to
RTU1 via Base RipEX; Base
RipEX
shortest possible time. Remote
RipEX1 receives the packet and
hands it over to RTU1, simultan-
eously acknowledging packet re-
ceipt to the Base RipEX.
Step 3
RTU1 processes the request and
RipEX Radio modem & Router – © RACOM s.r.o.
packet transmits in