Operating instructions

10 1892 1335 - Orion Radio Modem Operating Instructions - v2.9 / Aug 2009
Mode U - Data Only
The Orion can be used as a high-performance data modem without using its built-in telemetry
capabilities, and can be ordered without telemetry hardware at a saving in cost. Mode U
supports half-duplex or simplex serial User Data communication via Serial Port A.
Typically, two modems will communicate half-duplex, but other topologies are possible:
v Using the address facilities of the Orion, many such pairs may share a
frequency (on a time-sharing basis).
v Many modems may report data one at a time to a central modem provided
traffic is relatively light, or one modem may broadcast to all the others.
There is no concept of Base and Outstation because each modem initiates transmission
when it has data, rather than being polled. Addressing is described in detail on page 14
Depending on the throughput required and the level of errors which can be tolerated, different
over-air protocols may be selected. These are described on page 27.
Port A may be configured for various serial interfaces. See pages 19 (description) and 33
(connections).
Mode U parameters are covered on page 24, and radio configuration on page 27.
Contention can be dealt with / overcome by using a packet over-air protocol with
acknowledgements or by external equipment.
Mode R - Repeater
In order to extend the range of a link or network, an additional Orion (one per Group) can be
used as a repeater. Set to Mode R, it stores any message it receives for a member of its
Group and retransmits it without alteration. A duplicate message received by any unit is
recognised as such and ignored.
A repeater has an extremely limited range of behaviours, but can be programmed to raise
housekeeping alarms (page 16). It must belong to the same Group as it serves.
No telemetry or User Data input/output is available at the Repeater itself.
A repeater can be used in a network which uses any over-air protocol except Packet (TP),
but must be set for the same protocol as the units which it serves. Over-air protocols are
described on page 27.
Mode I - Independent Telemetry
The Orion has four digital inputs and outputs and four analogue inputs and outputs. Mode I is
used where these inputs and outputs simply need to be relayed from one location to another,
and no external SCADA (Supervisory, Control And Data Acquisition) equipment is to be
used. User Data can still be carried in addition to the telemetry.
The simplest arrangement is a one-to-one link where inputs at one end are mimicked at the
other end and vice versa. Two ways of working are possible:
v Each unit volunteers any change in its inputs to the other spontaneously, and the
other replies with an acknowledgement