Wood and Douglas 1335, Operating Instructions Manual

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1892 1335 - Orion Radio Modem Operating Instructions - v2.9 / Aug 2009
ADDRESSING
In order that you can create systems containing two or more Orions, or even several separate
systems, all on the same frequency, the Orion supports addressing. This works by having one
or more groups each containing between two and 254 Orion units. Each Orion bears the
number of a group to which it belongs, and its own unique number within that group. By
including both IDs in a message, it is possible to identify the specific unit for which a message
is intended. The sending unit’s identity is also included with the message so that the unit can
reply.
Each Group has a GroupID of between 1 and 254. (The remaining two values, 0 and 255,
are reserved for special purposes.) You can assign units to a Group by giving the same
GroupID to all of them.
Each Group has one Base unit defined by having the UnitID 0 (zero). Other units in the Group
must be designated as Outstations by entering a UnitID of 1 to 254, unique within the Group.
(The remaining value, 255, is reserved for special purposes and never used as a UnitID.)
With exceptions treated below, units only respond to messages addressed with their own
GroupID and UnitID.
Units also have a DestinationID ( DestID ), which is the address (UnitID) to which they will send
any message (User Data or telemetry) which they initiate . When replying , a unit always
addresses the unit which sent the message: DestID is not used.
Example:
Two Orions are used as a two-way link for User Data between A and B
Orion A: Base: GroupID=1, UnitID=0, DestID=1
Orion B: Outstation: GroupID=1, UnitID=1, DestID=0
Unit A sends a message containing the address “GroupID:1, DestID:1, SourceID:0" It
has inserted its own GroupID; its DestID as the unit to receive the message; and its
own UnitID as the source of the message.
Unit B receives the message and accepts it, because GroupID and DestID match its
own GroupID and UnitID.
Unit B needs to reply, so constructs a message with its GroupID, a destination not of its
own DestID, but of the SourceID of the incoming message; and its own UnitID as the
source of the message.
The DestID 255 has the special meaning of a broadcast, and messages with this address are
accepted by all units in the same Group. Broadcast messages are never acknowledged or
replied to, even if the system is set up to acknowledge normal messages.
v Therefore, Broadcast messages must not be used when Packet over-air
protocol is used.
The GroupID 0 causes a message to be accepted by all units except repeaters, ignoring both
GroupID and DestinationID - that is, the network does not use addressing at all.
v This code is not intended for use as the GroupID of telemetry Outstations, which
should send messages only to the Base.