K-Patents PR-21-S - Manual (Page 117)

11 Ethernet connection specification 111
Request format
The client to server communication, i.e. the requests sent from your computer to
the DTR, is in binary format. The request packets contain the following binary data
(all integers are in the network order, MSB first):
− 32-bit integer: packet number
− 32-bit integer: request ID
− (any): request data (depends on the request)
− (any): fill-in data
Important: The maximum size of the message is 1472 octets (bytes).
The packet number is echoed back by the DTR, but not processed in any way. The
packet numbers do not have to be sequential, any 32-bit value is valid.
The request ID is a 32-bit value that identifies the requested function, for example
sensor information. See Section 11.5.2 for request IDs.
The request data consists of 0 to 1464 octets of additional data associated with
the request.
The fill-in data can be used to increase the number of octets in a message. Any
number of NULL characters (0x00) may be added to the end of the request as long
as the total size of the message does not exceed the maximum of 1472 octets. This
may be useful, for example, if the client implementation uses fixed-length packets.
Response format
The response data sent by the DTR is in ASCII format. With the exception of the
packet number, the data is human-readable. The data structure is very simple:
− packet number (32-bit integer)
− zero or more lines of ASCII (text) keys and values associated with these keys
(for example temperature key and process temperature in Celsius)
The packet number is echoed back without change. The client (software on com-
puter) can use the packet number to check the response against the packet number
of the request.
The message text consists of lines of text, each line a single key (of one word) and
its value or values. The values are separated from the key by an equal sign ( = )
and multiple values are separated by a comma. White space (space or tabulator)
is allowed anywhere except within a single value or key name.
If the response consists of a character string, it is enclosed in double quotes (").