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Event Script Language (ESL)

Event Script Language (ESL)

sep 03, 2021

Event script language (ESL)

ESL is an easy procedural language adapted to work in the D2000 System environment. It allows implementing a wide scale of algorithms, which are necessary when creating the system application in a technological environment.

Basic features:

  • own algorithm is expressed in text form, as a source text (script),

  • basic (and integral) executive unit of the language is action,

  • allows to implement and call procedures within one script,

  • calling other scripts by means of the procedural method,

  • error state handler,

  • starting external processes,

  • declaration and use of global and local variables (within the frame of procedure),

  • work with values of objects, using them in expressions, changing them,

  • according to the context of script usage (Script, Active picture), it provides additional possibilities,

  • use of system objects in a specific way:

    • Historical value - work with the archive (read, block read, write),

    • Database - access to SQL database (read, write, delete),

    • I/O tags - reading, writing,

    • Pictures, Graphs, Compositions - to open, and close on the D2000 HI process's desktop,

    • HI process - communication with operator - text messages, queries,

    • Structured variable - work with structure items,

    • Alarms - to block or to acknowledge,

    • External function - calling external functions implemented in DLL libraries,

    • Process - communication with a process by means of text messages (COMMAND).