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).
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