EditingHoldModules < OpsRes

---+ Editing Hold Modules

_Hold_ modules belong to the _Advanced Process_ template (if you cannot find this template you may need to [[AttachArenaTemplate][attach it]]). After you have added a _Hold_ module by dragging it onto the flowchart view, you can edit it by double clicking. You can change the _Name_ of course, but the main functionality is determined by the _Type_. There are 3 types of _Hold_ module and we will discuss each one of them separately.

---++ Wait for Signal

This hold stores entities in a queue until a unique signal is recieved during the simulation. Each time the signal is received an entity leaves the _Hold_ module queue.

Consider the example of simulating cars queing at a parking building exit while waiting for their prepaid parking tickets to be approved. The cars ( _entities_) must wait for the signal 10 to be sent in the simulation. When this signal is sent, one car will proceed through the exit.

<img width="320" alt="Hold_for_signal.PNG" src="%ATTACHURL%/Hold_for_signal.PNG" height="263" />
---++ Scan for Condition

This hold stores entities in a queue until a condition is satisfied. However, the _Hold_ module ONLY checks this condition WHEN A CALENDAR EVENT OCCURS. If the condition is true then the first entity in the queue may leave the _Hold_ module. This generates a new event and the condition is checked again. Each time the condition is true an entity leaves the _Hold_ module queue.

Below is an example of a _Scan for Condition Hold_ module from the case study: [[CourierServiceModel][Courier Service Model]].

<img width="320" alt="Hold_Scan_for_Condition.PNG" src="%ATTACHURL%/Hold_Scan_for_Condition.PNG" height="263" />
---++ Infinite Hold

This hold stores entities in a queue infinitely while the simulation is running.

_NB:_ An infinite hold is usually combined with a _Search_ module and a _Remove_ module (See Arena help for more details).

Consider the example of simulating an emergency waiting room. Incoming patients (entities) are placed into a queue based on their Patient Type. Patient Type is an attribute assigned to each entity earlier in the model. Patients will wait in the Emergency Room module in queue until they are removed from the queue by an nurse (entity) from a Remove module.

<img width="320" alt="hold_infinite.PNG" src="%ATTACHURL%/hold_infinite.PNG" height="263" />

-- Main.MichaelOSullivan - 25 Aug 2009
This topic: OpsRes > WebHome > ArenaGuide > EditingHoldModules
Topic revision: r8 - 2010-02-04 - KatTrevor