Specifications

Sheet 10 of 39 Document 12245 Rev. I
Where more than one data value is sent, they are usually separated by some delimiter such as a comma (“,”
ASCII code 2C).
The following are descriptions of the most commonly used types of data:
2.2.1 Analog Value
An analog value represents a numeric measurement, control, or setting such as currents, voltages, gain, etc.
Analog values are formatted as an ASCII string containing the numeric value. Analog data can be a floating-
point value (e.g. “3.12”), or an integer value (e.g. “14”). The data can be signed (preceded by a “+” or “-”) or
unsigned (no sign character preceding).
The ASCII characters recognized are digits “0” - “9”, the decimal point (“.”), and a sign (“+” or “-”). Only one
decimal point may appear, and the sign, if any, must appear at the beginning of the string. Any other
character will terminate the number. Exponential notation (“X.XXXE+YY”) is not used.
Overrange and underrange values are preceded by a “>“ or “<“ symbol, respectively.
If the measurement is unavailable for some reason, a question mark (“?”, ASCII code 3F) will be returned. If
more than one data value is included, values will be separated from one another by commas (“,”, ASCII code
2C).
In protocol documents, the following symbols will be used to represent analog data being sent in the message
body:
N
label
an unsigned floating point value
±N
label
a signed floating point value
I
label
an unsigned integer value
±I
label
a signed integer value
label will be text representing the function of the value.
2.2.2 Enumerated Value
An enumerated value can be represented as one of two or more states. For example, an amplifier may be
“ON” or “OFF”. Enumerated values are represented by a single byte. Each possible state is represented by a
different value. Usually the ASCII code for “0” (30) is used to represent NO, OFF, FALSE, etc. and the ASCII
code for “1” (31) is used to represent YES, ON, TRUE, etc. Other codes may represent other conditions, such
as “?” (3F) for “unknown”.
In cases where more than one enumerated value is sent, each value is represented by a single byte, with no
delimiter between them. However, enumerated values will be separated from other data values by a comma
(“,”, ASCII code 2C).
In protocol documents, the following symbol is used to represent enumerated values in the message body:
B
label
A single enumerated value
label will be text representing the function of the value
A brief description of the meanings of the values for each byte will follow.
2.2.3 Bit Flag Value
Groups of flags representing simple YES/NO or TRUE/FALSE data are represented as bits in a single byte.
Bit flag values are transferred in the least significant six bits of a byte (bits 5 through 0), with the most
significant two bits being 0 and 1 (bit 7 is 0, bit 6 is 1).
In cases where more than six bit flags are needed, more bytes are sent, with no delimiters between them.
However, bit flag values will be separated from other data values by a comma (“,”, ASCII code 2C).
In protocol documents, the following symbols are used to represent a byte of bit flag value data in the
message body: