ODiSI 6
ODiSI 6
User’s Guide
Page 82
Segment Vector
A segment vector is an array of multiple contiguous gage values. A segment is defined by
specifying the location of the first gage and the number of gages in the vector.
All segments will use the same spacing between gages, which is defined by the properties of
the ODiSI test and the properties of the sensors.
Streaming Connection
The ODiSI streams data over a TCP/IP connection. The TCP/IP port can be configured; the
default port is 50000.
Upon configuration by the user, the ODiSI device opens a port and begins listening for a client
connection. The client program will initiate a TCP connection to the ODiSI server on the
specified port number. As soon as a connection is established, the ODiSI will begin sending
messages to the client.
If at any time the ODiSI loses connection with the client, it will resume listening for a new client
message and will resume sending data once a new connection has been established. The
ODiSI will not send measurement data that was missed during the time the connection was
down. If the user has enabled test data logging to file, the data will still be available in the
saved test data file.
The application data is one way. That is, the ODiSI sends data to the client but does not look
for any responses.
Each new message starts at the beginning of a new TCP packet.
Message Types
Four types of messages are transmitted over the streaming protocol: an initial
acknowledgement, a Measurement Message, a Metadata Message, and a Tare.
The initial acknowledgement is returned when the client first connects. A metadata record is
returned informing the client that it has connected to the ODiSI Controller.
The Measurement Message is a simple format, consisting mostly of an array of numeric data
which represents the measured strain and temperature gage values. The metadata needed
to fully interpret the data (gage and segment names, locations, units, etc.) require too much
space to be transmitted with every measurement and are instead transmitted less frequently
within the Metadata Messages. The Tare message contains the value of the tare that was
applied to the measurement; it is provided for informational purposes.
All message types use JSON formatting. This data is human readable text, encoded as UTF-
8. The language of the JSON fields is always English, and is not affected by the language
selection made in the main software. However, all fields that hold user defined values (test
name, sensor name, gage name, segment name) support the full UTF-8 character set.
User defined values will use an escape character to encode quote marks and backslash
characters (if they appear in the user data). A quote mark is represented as
\
”
in the JSON
string. A backslash is represented as
\\
. These are the only characters that need to be escaped
