Specifications

Chapter 10
Extended Addressing
The D1000 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-charac-
ter 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 D1000:
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 address-
ing range of 249 points.
Structured Addressing
Even for a relatively small system, it can be advantageous to employ a
hierarchical addressing system as used in Fig. 7.1. This is particularly
true in systems that consist of many sites that are identical. From a host
software standpoint, each site can be treated identically with the same
module addresses, with each site having a different D1000 address.
Extended Address Syntax
The command syntax used with Extended Addressing is quite similar to
the normal protocol. The Extended Address commands are initiated with
a '{' character (left curly brace, ASCII $7B), or a '}' character (right curly
brace, ASCII $7E). The '{' prompt is analogous to the '$' prompt in that it
returns the shortest possible response to complete the command. The '}'
prompt is similar to the '#' prompt in that the command is echoed and a
checksum is generated along with the other data necessary to complete
the response. The '*' response prompt is used in all command forms.