Tait T2000-A75, Руководство по эксплуатации, Страница: 17 / 38

November 2001 M2256-000-00-051 17
4 Command Mode Operation
Message Format
All Command mode message packets take the general form:
[IDENT] [SIZE] [PARAMETERS] [CHECKSUM] <CR>
• All characters in a message are printable ASCII.
• Where numeric values are represented in ASCII-hex notation (two characters per byte),
characters A to F are upper case.
• The minimum length of a command packet is 5 characters. For example q002F is the
QUERY command where [SIZE] = 00 as there is no [PARAMETERS] field required.
• The maximum length of the [PARAMETERS] field is 42 characters. The maximum length
of the command packet is therefore 47 ([SIZE] = 2F) characters.
Example
#12C401060A010000BASE8F
1. # is the message [IDENT] for a PROGRAM command.
2. 12 is the parameter [SIZE] as there are 18 characters of data to follow in the [PARAME-
TERS] field.
3. C401060A010000BASE are the data bytes in the [PARAMETERS] field.
4. 8F is the calculated checksum of the message line.
5. The actual data that is sent out the port in hexadecimal form is:
23 31 32 43 34 30 31 30 36 30 41 30 31 30 30 30 30 42 41 53 45 38 46
Field Description
[IDENT] The message identifier. Identifiers are single ASCII characters (lower-case alphabetical)
which categorise the message type.
[SIZE] The number of characters which make up the [PARAMETERS] field. [SIZE] is an 8-bit
number expressed in ASCII-hex notation (two characters).
[PARAMETERS] An optional field, depending upon the command. Parameter values are generally character
strings unless explicitly stated otherwise. Parameter type is dependent upon the command
- there is no explicit type definition.
[CHECKSUM] An 8-bit checksum of the [IDENT], [SIZE] and [PARAMETERS] fields. Expressed in two
character ASCII-hex notation.
<CR> The carriage return packet terminator.