Vif

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Arbitrary Syntax Tree ​

The ast syntax is built with following principles:

  • As simple as possible, the tokens should describe exactly what your code is supposed to do.
  • Human readable, in a format that everyone knows (JSON).

Trace ​

vif-language-builder uses the stacktrace-js package to keep a trace of where the source and all operations are created.

To be efficient, vif only keeps the path starting from the working directory. For example the following path:

text
C:\Users\AnyUsers\WorkingDir\VifProject\Plc\Root.ts

Will be simplified to

text
\Plc\Root.ts

Any trace structure have the keys file, line, column.

json
{
  "trace": {
    "file": "\\Plc\\Root.ts",
    "line": 20,
    "column": 5
  }
}

INFO

Trace is not a mandatory field, vif-sim will return it if an error was thrown, but tracing objects do not alter the simulation behavior.

Monitor ​

Only variables which are statically instanced can be monitored. Each variable is an array of string which describe a path starting from the simulation root.

json
{
  "monitor": [
    ["MyInstanceDb", "variable"],
    ["MyGlobalDb", "my_array", "[0]"]
  ]
}

INFO

If a variable could not be solved, vif-sim will send a warning.

Files ​

Each block is represented with the [file URI scheme](https://en.wikipedia.org/wiki/File_URI_scheme.

json
{
  "file:///Root": {},
  "file:///Folder//AFbBlock": {},
  "file:///AnotherFolder//NestedFolder//AFcBlock": {}
}

Program blocks ​

All program blocks have a ty and a src keys.

json
{
  "file:///Root": {
    "ty": "fb", //Or ib, fc, global_db, instance_db
    "src": {
      "interface": {
        // All the sections and variables associated
      },
      "body": [
        // All operations
        // This key is only availble in ib, fb, and fc blocks
      ]
    }
  }
}

Udt ​

Udts also have a ty and a src key.

json
{
  "file:///IEC_TIMER": {
    "ty": "udt",
    "src": {
      "name": "IEC_TIMER",
      "interface": {
        // No sections
        // All variables are created directly
      },
    }
  }
}

Trace ​