Loading Point
Overview and Key Concepts
The loading point represents a location at which a loading or unloading operation takes place, such as a ship jetty or truck loading lane. There are three modes of operation for the loading point:
- Manual: Using a manually controlled loading time, where transporters remain in the (un)loading state until you manually call the StopLoading command on them.
- Fixed time: Using a fixed processing times for the load or unload operation, somewhat similar to FlexSim's processor for flow items, with an additional option to include pre- and post-loading processes.
- By tank level: In conjunction with a loading controller, such as a loading arm or multi-compartment loading controller. The (un)loading time is automatically determined by the flow to or from a flow tank on the loaded item (ship or truck) - the loading controller monitors the fluid level in the transporter's tank and notifies the loading point when the operation is complete.
The Berth is functionally equivalent to the Loading Point, except the visualization and queue placement of transporters in the loading point is by default aimed at truck transports while the default settings of the berth are specifically tailored towards flow vessels.
Events
The loading point and berth use standard events that are common to a fixed resource such as a Queue or Processor. See Fixed Resource - Events page. In addition it has the following events:
On Start Preprocessing
This function is called immediately before the preprocessing starts, after the preprocessing time has been sampled. If no preprocessing has been specified (preprocessing time 0) this function will still be called, but it will be immediately followed by OnStartLoading.
It has the following parameters:
| Event Parameter | Explanation |
|---|---|
| item | A reference to the flow item (transporter). |
On Start Loading
This function is called when the preprocessing time of a transporter has ended and the loading operation (whether timed or controlled by a loading controller) is about to start.
It has the following parameters:
| Event Parameter | Explanation |
|---|---|
| item | A reference to the flow item (transporter). |
On End Loading
This function is called immediately after the loading or unloading has finished, and immediately before the postprocessing step starts. If no postprocessing has been specified (preprocessing time 0) this function will still be called, immediately followed by On End Postprocessing.
It has the following parameters:
| Event Parameter | Explanation |
|---|---|
| item | A reference to the flow item (transporter). |
On End Postprocessing
This function is called when the postprocessing time of a transporter has completed and the item is released from the loading point. Even if no postprocessing has been specified (preprocessing time 0), this event will still fire.
It has the following parameters:
| Event Parameter | Explanation |
|---|---|
| item | A reference to the flow item (transporter). |
States
Loading point states
Note that no flow goes through a loading point, so this object does not have a FloWorks state profile. For statistical purposes, the loading point's FlexSim default state profile will be in one of the following states at various points during a simulation run:
- Idle - The loading point is empty and is waiting for a transporter to enter.
- Busy - The loading point is processing at least one transporter.
If the loading point only accepts a single transporter because its capacity is set to 1, its state profile is more detailed:
- Idle - The loading point is empty and is waiting for the transporter to enter.
- Preprocessing - The loading point is in the preprocessing stage of the transporter.
- Busy - The loading point is in the loading stage of the transporter: either the (un)load time is running or the loading point is waiting for the loading controller to release the item.
- Postprocessing - The loading point is postprocessing the transporter.
- Blocked - The loading point has released the transporter, and is waiting for it to exit. The output may be blocked by a downstream object or - in theory - the transporter may be waiting for an operator.
Flow item states set by the loading point
In addition to the state profile of the loading point itself, the loading point also changes the (default FlexSim state profile) state of the flow items it processes. Regardless of whether the loading point has a capacity of one or more, the following flow item states are applied while the flow item is under the loadig point's control:
- Waiting - The transporter has entered the loading point but the "Max. simultaneous loading" capacity is reached so it has to wait before it can start preprocessing.
- Preprocessing - The transporter is in the preprocessing state.
- Busy - The transporter is being (un)loaded: either the (un)load time is running or the loading point is waiting for the loading controller to release the item.
- Postprocessing - The transporter is being postprocessed.
- Blocked - The loading point has released the transporter, which is now waiting to exit. It may be blocked by a downstream object or - in theory - waiting for an operator to pick it up.
Properties
The loading point and berth have five tabs with various properties. For more information about the properties on tabs, see:
The last four tabs are the standard tabs that are common to all fixed resources. For more information about the properties on these tabs, see:
Settings
Maximum content
The maximum number of items (vessels, trucks, etc.) that may be present at the loading point at the same time.
Loading maximum
The maximum number of items (vessels, trucks, etc.) that can perform loading or unloading simultaneously. As long as the maximum has not been reached, entering items may start their loading or unloading process. Once the maximum number of items is loading, new items may still enter (determined by the Maximum Content setting) but they will remain idle at the loading point. The next item will only start its (un)loading process when the previous item is exiting.
If more than one item is allowed, the pre-processing, (un)loading and postprocessing steps are seen as a single operation for the purposes of simultaneous loading. It is not currently possible, for example, to start pre-processing of the next item as soon as the loading step for the previous item finishes, if the previous item also has a post-processing step. The next item can only start pre-processing when the previous item has finished its post-processing. If only one item is allowed the Busy state of the object is seperated PreProcessing, Busy and Postprocessing.
Pre-processing time
This is the total time of all the processes that preceed the actual loading or unloading operation. Steps like manoevring and mooring (for vessels), connecting and preparation of cranes etc, and paperwork could be included here. The time may be specified as a constant time, using statistical distributions from the dropdown menu, or by writing custom FlexScript.
Use Loading Controller
The checkbox determines whether the loading point has a predetermined (un)loading time or whether an external loading controller, such as a loading arm or multi-compartment loading controller, will control the (un)loading duration. If the Loading Controller option is enabled, the default option is to use the first object connected by center port ('S'-connection) to the Loading Point.
(Un)loading time
When the "Use Loading Controller" checkbox is enabled, this field will be grayed out because the specified Loading Controller will decide when the flow item is released. Otherwise, you can specify the (un)loading time, either as a constant value, using statistical distributions from the dropdown menu, or by writing custom FlexScript.
If the expression evaluates to zero, the Loading Arm will not release the transporter, but wait for you to call StopLoading on it.
Post-processing time
This is the total time of all the processes that follow the actual loading or unloading operation. Steps like manoevring and unmooring (for vessels), disconnecting of cranes etc, and paperwork could be included here. The time may be specified as a constant time, using statistical distributions from the dropdown menu, or by writing custom FlexScript.