ODiSI 6
ODiSI 6
User’s Guide
Page 81
8
ODiSI Measurement Streaming Protocol (OMSP)
In the discussion of Streaming Properties above, the measurement data is streamed to and
analyzed in a separate client. This is accomplished using the ODiSI Measurement Streaming
Protocol (OMSP). Custom client code can be programmed to connect to the ODiSI 6 and
receive measurement data for display and logging.
The protocol consists of JSON-formatted data sent over a TCP/IP connection. JSON is a
lightweight data interchange format that is easy to read and parse and is supported in virtually
all programming languages.
OMSP consists of four message types:
•
An initial acknowledgment message when the connection is established. This
message type looks like an empty metadata message.
•
Metadata messages provide information about the ODiSI system, the active sensors,
and the names and locations of the gages that will be streamed.
•
Measurement messages contain the gage values generated from a single
measurement.
•
Tare messages contain the value of the tare that has been applied to the
measurements. This is provided in case the client wants to store information about the
tare or remove the effect of the tare on the data.
Terminology
The ODiSI measures strain or temperature at multiple points along a sensor.
Channel
The ODiSI acquires data from multiple channels (1 to 8 for the ODiSI 6). A different strain or
temperature sensor is attached to each channel. The channel number is used in OMSP to
specify which sensor is being referred to.
Sensor
An ODiSI sensor is used to measure either strain or temperature. Each sensor contains
thousands of different gages at evenly spaced intervals, at which strain or temperature
measurements are made.
All of the gages on a given sensor have the same measurement type (strain or temperature)
and units.
Gage
The ODiSI always calculates measurements at each gage along the sensor. Users can name
specific gages of interest, and use OMSP to stream those named gage values to another
program.
A named gage is defined by its name and its location on the sensor.
