TIAMIS-800 wireless radio transceiver
User Manual. Ver. 1.3
DOUM0003AA
Page 15 of 35
•
Listen and transmit – has at least one frame to transmit on;
•
Only transmit – has no frames when it receives messages from anybody in
the network other than the Master.
2.
Pure Point-to-Multipoint. In this case the FrameTable contains only two frames,
one of which is the Master’s and one other that is shared between all of the Slaves
in the network.
3.
Hybrid of the Point-to-Multipoint and the TDMA. In this case there is at least one
frame in the network dedicated to the Master; there is at least one frame dedicated
to one of the Slaves’ transmissions; and there is at least one frame to be shared
between two or more Slaves. The Slave with the dedicated transmit frame in this
case might ‘push’ its data while the Slaves, who are sharing frames, might be
‘polled’ by the Master (just like in the Point-to-Multipoint network).
We recommend choosing a TDMA network topology instead of the Point-to-Multipoint
if one of the following situations is true:
•
If the number of Slaves in the network is relatively high (100 or more).
•
If the Slaves are not ‘polled’ by the Master (Slaves ‘push’ their data) and each one
of them generates near continuous data.
•
If the Slave sites will most likely generate their data almost at the same time. For
example a network in which the Slave sites are equipped with GPS receivers.
On the other hand, one may find the Point-to-Multipoint network more suitable for an
application if each Slave site in the network is polled for its data by the Master.
3.4.2. Functionality of the TDMA Master
The Master in a TDMA network can send a new packet of data over the RF channel as
soon as at least one byte of the user’s data was received from the user’s data device.
Each RF packet, which the TDMA Master sends out, is broadcasted to all listening Slaves
as a Global_Packet.
Each RF packetwith or without user’s data is sent by the TDMA Master once and
repeated
PacketRepeat
times. Each copy of the original packet will be sent during the
Master’s next transmit frame. If a listening Slave receives such packet from the Master
followed by a copy of the same packet, the Slave will discard the additional copies
automatically without delivering a copy of the user’s data to the data port.
There are several Master settings, which must be repeated or considered when setting up
the Slave radios to operate in the same network. Below are
the Master’s settings, which
need to be matched by the recipient Slave radio(s) in the network:
•
Each Slave in the network must have its
Recipient_UnitID
matching the Master’s
my_UnitID
.
