Specifications

Document 12245 Rev. I Sheet 11 of 39
01 b
lb5
0 b
lb3
b
lb2
1 b
lb0
lb
x
will be a label that identifies the function of each bit
0 represents bits that are not used, and that will always be set to 0.
1 represents bits that are not used, and that will always be set to 1.
Brief descriptions of the meanings of each bit when it is SET (1) will follow.
2.2.4 String Value
Text data, such as the firmware version and mask number, is represented simply as a string of ASCII
characters.
In cases where more than one string value is needed, the values will be delimited. The delimiter used will be
identified in the protocol document for the particular piece of equipment.
In protocol documents, the following symbol will be used to represent string data in the message body:
“label”
label will be text identifying the function of the string value
Note that the quotation marks are shown here only to identify a string value, and are NOT actually present in
the message body.
2.2.5 Protocol Symbols
As shown above, certain symbols are used in protocol documents to represent different types of data values.
In addition, other notations have other meanings:
[ ] Brackets enclose segments of the message body that may or may not be present. The
brackets may be nested.
... Ellipses represent that more than one of the same type of value may present in the message
body.
2.3 Programming Issues
2.3.1 Compatibility
The contents of any message are subject to change as features and improvements are made to the product
line. Therefore, changes to the protocol may be necessary. Wherever possible, the changes will be made in
such a way as to maintain compatibility with existing systems, provided the following rules are followed:
Make no assumptions as to the range or step size of any analog value.
E
XAMPLE: If a gain setting can currently be controlled from 0 to 20 dB in 0.1 dB steps, the range may
be extended to 30 dB in the future, or the step size may be changed to 0.05 dB.
Allow for extra data values to be returned at the end of any message, or at the end of a group
of enumerated or bit values delimited from other values.
It is not necessary to predict the meanings of such values, but their presence must be tolerated. The
original values will be left in the same positions and order in the message body, new ones will be
added to the end.
E
XAMPLE: If a message currently returns 3 Analog Values, a fourth may be added to support a new
feature in the future.
Allow for extra codes (not currently documented) in enumerated values.
Again, it is not necessary to predict the possible meanings of such codes, but code values other than
those listed should be tolerated. The meanings of existing codes will be left unchanged.