1.6.2 General file format

The protocol definition language uses a file format which is very similar to that one used with sat-nms device drivers. Like with device drivers the following applies:

• Whitespace (space characters, tabs, line breaks) separates words.
• Line breaks have no special termination function.
• All keywords are in upper case letters.
• Comments in C/C++ style are recognized (both, /* ... */ and // ... comments).

Beside this, each protocol definition file has the same simple structure:

• The file starts with an (optional) comment block and some common definitions.
• Then, following the TRANSMIT keyword, the specification how a message shall be composed during transmit is given.
• Then the RECEIVE keyword starts the specification how to parse incoming data.

Below, an example for a protocol definition file is shown.

//
//  The communication protocol used with SSE devices in NPI mode. 
// 

COMMENT  "SSE-NPI 1.00 020108"
CLASS    TTYProtocol


/** packet send procedure ************************************************/

TRANSMIT

   CHAR        2                // start byte, STX
   CHAR        "F"              // source (master) LU
   CHAR        "F"
   ADDRESS     TEXT             // destination (slave) LU, 2 characters
   HEXLENGTH   0                // 2 characters hex coded data length
   USERDATA                     // the command string
   CHECKSUM    SUM8H 1 -1       // checksum 2 characters
   CHAR        3                // end byte, ETX

/** packet receive procedure *********************************************/

RECEIVE

   START       2                // start byte, STX
   ADDRESS     TEXT             // source (slave) LU
   CHAR        "F"              // destination (master) LU
   CHAR        "F"
   HEXLENGTH   0                // 2 characters hex coded data length
   USERDATA                     // the response string
   CHECKSUM    SUM8H 1 -1 2     // checksum 2 characters
   CHAR        3                // end byte, ETX