DateTime

A Modelica-native library for calendrical dates, times, and scheduling.

DateTime bridges the gap between Modelica's relative simulation clock and the real-world calendar. Drop a single DateTimeSystem component into your model and gain access to absolute dates, timezone-aware scheduling, daylight saving transitions, workday logic, and repeating calendar events — all without external C libraries.

Project status

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Key Capabilities

Capability	What it does
Time mapping	Convert simulation time to absolute dates and vice versa
Event scheduling	Trigger at ISO 8601 dates with Schedule
Repetition rules	hourly, daily, weekly, workdays, monthly, and more
Timezone support	200+ predefined IANA-style timezones with DST transitions
Holiday / workday logic	Define holidays and workweeks; schedules respect them automatically

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Minimal Example

model MyModel
  inner DateTime.DateTimeSystem dateTimeSystem(
    startDateTime = "2025-10-03T08:00:00",
    timezone      = DateTime.Data.Timezones.Europe.Berlin,
    holidays      = {"2025-12-25", "2025-12-26"});

  DateTime.Basic.SimDateTime simDateTime;

  DateTime.Basic.Schedule dailyTrigger(
    triggerDateTime = "2025-10-03T09:00:00",
    onTime          = 3600,
    repetition      = "workdays");
equation
  // simDateTime.year, .month, .day, .hours, .minutes, .seconds
  // dailyTrigger.y is true for 1 h every workday at 09:00
end MyModel;

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Getting Started

1. Clone the repository:

   git clone https://github.com/pstelzig/DateTime.git
   

2. Load src/DateTime/package.mo in your Modelica tool (tested with OpenModelica >= 1.25).
3. Place an inner DateTimeSystem in your top-level model and configure the start date, timezone, and holidays.

See the Getting Started Guide for a detailed walkthrough with examples.

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Documentation

Document	Contents
Getting Started	Installation, integration, and usage examples
Design Overview	Architecture, rationale, and component reference
Timezones & Scheduling	Timezone data, ISO 8601 conventions, DST, leap seconds

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Status

The library is in active development. Core functionality — date/time conversion, timezone handling, and scheduling — is implemented and covered by unit tests. Leap second support is experimental.

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How to Cite

@misc{stelzig2025datetime,
    author       = {Philipp Emanuel Stelzig},
    title        = {DateTime: A Modelica-native library for dates, times, and scheduling},
    year         = {2019--2025},
    howpublished = {\url{https://github.com/pstelzig/DateTime}}
}

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License

Developed by Dr. Philipp Emanuel Stelzig under the MIT License.

Copyright © Dr. Philipp Emanuel Stelzig, 2019–present.