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).