====== 02 Getting Started ======

===== Installation =====
The easiest way to get started with the HSE State Machine is by [[code:dqmh:hse-module-templates:overview#installconfigure|installing and using it]] as a module template. However, the State Machine implementation is not restricted to be used inside a DQMH module. To use it in an already existing project, follow these steps:

  * download and unzip the latest source distribution from our [[code:dqmh:hse-module-templates:releases|Releases page]]
  * open the ''TEMPLATE.lvproj'' and navigate to ''StateMachine.lvlib''
  * right click on ''HSE-State-Machine.lvlib'' and select ''Save'' --> ''Save As...''; uncheck ''Add copy'' options and follow the dialog
  * open your existing project and add the newly saved lvlib
  * open ''SM DEMO.vi'' and copy the ''State Machine Loop'', ''SM Create Event'' and ''SM Destroy Event'' to your Block Diagram as needed
  * remove / replace the following dependencies from your project as needed
    * ''SM DEMO.vi''
    * HSE Logger in ''SM Wait for Transition.vi''
    * DQMH Message Queue in ''SM Update UI State.vi''
    * DQMH Message Queue in ''SM Process Exception Transition.vi''

===== Adaption =====
  * edit ''SM_States.ctl'' to reflect the needed states for your project
  * edit ''SM_Transitions.ctl'' to reflect the needed transitions for your project
  * implement states and transitions as needed
    * create a case for every state
    * in each state, create a case fo each **allowed** transition
    * in each case, which defines an allowed transition, define the next state and, if needed, trigger an action calling a MHL case
  * call ''SM Request Transition.vi'' in MHL or EHL as needed to request transitions

===== Communication to the State Machine =====
{{ :code:dqmh:hse-module-templates:pasted:20210720-074228.png?650 |Local Events used for request transitions}}

Communication to the State Machine Helper Loop takes place over a local user event. The event reference is created when the module starts and destroyed afterwards. The events can be triggered from the Event Handling Loop (EHL) and the Message Handling Loop (MHL) to request a transition. For transitions, we always use the verb ''request'' and not ''trigger'', indicating that a transition only informs the state machine about a command or something that happened. Only the state machine itself decides if this transition will actually change its state.

{{ :code:dqmh:hse-module-templates:pasted:20210720-085843.png?650 |Request a transition from the MHL}}