Data Stream Protocol

The data stream module takes an incoming raw data stream and splits it into multiple data streams. The data stream format is specified by a configuration file provided by the user.

Parent topic: Protocols

Configuration Format

The configuration file is a comma-delimited text file that specifies one data variable per line. Each line starts by specifying the data format of the variable by one of the tags presented in the table below. The position of the variable in the output grid is then given by two coordinates starting at index 1. The final parameter assigns a text string to the variable.

Table 1. Data Stream Types
Type Size Tag Example
Unsigned byte 1 B B,1,1,Light
Signed byte 1 -B -B,1,1,Encoder
Unsigned short 2 D D,1,1,ADC
Signed short 2 -D -D,1,1,ADC
Unsigned word 4 W W,1,1,Transfer rate
Signed word 4 -W -W,1,1,Status code
Floating point 4 F F,1,1,Temperature
Double-precision floating point 8 DF DF,1,1,Measurement
Grid of unsigned bytes 1 * W * D GB<WxD> GB<10x10>,1,1,Surface
Grid of signed bytes 1 * W * D -GB<WxD> -GB<10x10>,1,1,Surface
Grid of unsigned short 2 * W * D GD<WxD> GD<10x10>,1,1,Surface
Grid of signed short 2 * W * D -GD<WxD> -GD<10x10>,1,1,Surface
Grid of unsigned word 4 * W * D GW<WxD> GW<10x10>,1,1,Surface
Grid of signed word 4 * W * D -GW<WxD> -GW<10x10>,1,1,Surface
Grid of floating point 8 * W * D GF<WxD> GF<10x10>,1,1,Surface
Grid of double-precision floating point 8 * W * D GDF<WxD> GDF<10x10>,1,1,Surface

This is an example configuration: 

                D,1,1,ADC0
                D,1,2,ADC1
                D,1,3,ADC2
                B,2,1,Prescaler

Stream Format

The data stream is processed in the same order as the configuration file specifies. All data must be given as little endian values, meaning that the lowest byte must be sent first. Additionally, a wrapper consisting of one byte before and one byte after the data stream variables must be added. This wrapper is used by the interpreter to synchronize to the data stream. The start byte can be of an arbitrary value except 0x5F, which is reserved for Auto-Configuration, but the end byte must be the inverse of the Start byte. For more information on the Auto-Configuration feature see Auto-Configuration and Auto-Configuration Example. The configuration file shall not define the start and end bytes.

Consider the example configuration given in the previous section. The figure below gives an example raw data transmission where ADC0 is 185, ADC1 is 950, ADC2 is 0, and Prescaler is 2.
Figure 1. Data Streamer

Basic Usage

Figure 2. Data Streamer