Omega A2400 - Manual (Page 53)

Chapter 9
Extended Addressing
The A2400 may be configured to a special command format called Extended
Addressing. This mode uses a different prompt, either ‘{‘ or ‘}’ to distinguish
it from the regular command syntax. The major difference in syntax for the
Extended Addressing mode is that it uses a two-character address. A typical
command in Extended Address mode would look like this:
Command: {01WE
Response: *
Both the command and response are terminated with carriage returns. Note
that the command uses a two-character address, ’01.’
There are two benefits to using Extended Addressing with the A2400:
1) Greatly expanded addressing capability.
2) Allow for a more structured addressing method in
large systems.
With single-byte addressing of the normal command structure, address
space is limited to 122 points. Extended addressing allows an addressing
range of more than 1.8 million points. More realistically, if only printable
characters are used for addresses, the total address range is more than
700,000 points.
Open/Close Channel Commands
From an operational standpoint, A2400’s with Extended Addressing are
used differently than A2400’s with normal addressing. An A2400 configured
to Extended Addressing acts as a ‘data gate’ that controls the data that may
appear on the RS-485 bus. This ‘data gate’ may be turned on and off with
the Open Channel (OC) and the Close Channel (CC) commands.
Refer to Figure 7.1. This illustrates a small system of two remote radio sites,
each with an A2400 and two modules. Note that the two modules have
identical addresses at each site. The radio modems are effectively ad-
dressed by the A2400’s, one with an address of ‘01’ and the other address
‘02’.