Generating Time Horizon - driven SILS Supply Messages

Time horizon driven supply is one of the two methods to generate or update assembly part supply messages. The other method is to use triggers, defined in a process-triggered workflow. For example, the completion of a previous LSO can be defined as a trigger to run the Replenish Shop Floor Warehouse (tiasc8210m000) session.

If you use time horizon driven supply, you have several advantages. For example:

  • You can generate supply messages before the start of the first LSO, because you are not dependent of previous trigger events.
  • You can generate supply messages independent of variations in cycle time.
  • You can generate supply messages independent of line structure changes.
  • You can skip the maintenance of triggers, which can become a rather complex business.

However, the disadvantage is that you only have planned assembly data as basis, and not actual data. If it is vital to act on start dates/times and job sequences that are (nearly) actual, in a situation where you cannot update the planned data, you must use triggers. Triggers, after all, are always based on the actual progress of the assembly order. It is also possible to use both methods, as is explained below.

Prerequisites

To generate or update supply messages for an LSO, the following conditions must be met:

  • The LSO falls in one of the time fences that are defined for the assembly parts contained in the LSO.
  • At least one of the check boxes Generate Messages or Regenerate Messages is selected. (If both check boxes are cleared, supply messages are only unblocked, for LSOs that fall in the Last Update Time Fence.)
  • The status of the LSO must be less than Completed.
  • The status of the assembly order that contains this LSO must be Sequenced or In Progress.
Functionality

If you run the current session, supply messages are generated or updated, according to the time fence the LSOs fall in, and the check boxes you select in this session. Each time fence is defined as a number of working days or hours before the planned start date/time of the LSO. Therefore, the time fences partly overlap each other.

The following time fences exist:

  • Generate Time Fence If LSOs fall in this time fence, supply messages are generated or updated for these LSOs.
  • Frozen Time Fence This time fence indicates when the content of an LSO is frozen, which means that no changes in materials or quantities are allowed, because the warehouse or supplier cannot proces this kind of changes anymore. However, changes in delivery sequence and delivery date/time are still accepted.
  • Last Update Time Fence Supply messages in this time fence cannot be updated anymore and in any respect. The current session only unblocks the supply messages for LSOs that fall in this time fence. Unblocking is explained in one of the paragraphs below.

The time fences are defined on the KIT that contains the assembly parts, in the Assembly Kit (whwmd4150s000) session, which you can start by double-clicking a record in the Assembly Kit (whwmd4550m000) session, in Warehousing. The current session checks whether the selected LSOs fall in one of the time fences that are defined on the KIT of the required parts.

Post-requirements

After you generate or update supply messages, you must transfer them. To transfer the supply messages, run the Transfer Assembly Part Supply Messages (tiasc8220m000) session. When the messages are transferred, they are processed.

The way the supply messages are transferred and processed is determined by the Supply-from Warehouse check box in the Warehouse - Item (whwmd2110s000) session:

  • The check box is selected for internal supply. LN generates warehouse transfers from the source warehouse to the shop-floor warehouse.
  • The check box is cleared for external supply. The Purchase Control module uses this information to generate a sequenced shipping schedule to control supply from the supplier to the shop floor warehouse.
Blocking

Supply messages for internal supply are generated with the Blocked status. The warehouse orders that result from these messages also have the Blocked status. Blocked warehouse orders are not processed, although they can be used for scheduling and reservation purposes. The warehouse orders are unblocked when you transfer unblocked update messages. Unblocked messages are generated, for LSOs that fall in the Last Update Time Fence, when you run the current session. Note that when you run the current session, you always generate last updates of supply messages, for LSOs in the selection range, that fall in the Last Update Time Fence, even if the Generate Messages check box and the Regenerate Messages check box are cleared. The last update can also be performed by the Replenish Shop Floor Warehouse (tiasc8210m000) session. The status of the supply messages is displayed in the Line Station - Assembly Part Supply Transfer (SILS) (tiasc8520m000) session.

Relation between triggers and time fences

It is possible to use both triggers and time fences. If you use both methods, the relation between these methods is as follows:

  • The session that is first executed, generates the supply messages. So, if the trigger is defined before the execution of the current session, the Replenish Shop Floor Warehouse (tiasc8210m000) session generates the messages. The trigger does not take into account the Generate Time Fence, and therefore can be defined before or in this time fence. If the current session is run in the Generate Time Fence, and before the trigger, the current session generates the supply messages.
  • The supply messages can be updated by both sessions, and both sessions take into account the Frozen Time Fence. So, there is no difference in this respect. Only the update of the messages by the current session requires that the selected LSOs are not yet in the Last Update Time Fence.
  • Which session performs the last update, and of what character the update is, depends on the sequence in which the sessions are executed, the way the last update is defined, and the relation to the Last Update Time Fence. Because it is too complicated to summarize the different situations, it is better to keep in mind the following rules, which determine what happens:
    • The current session updates before the Last Update Time Fence and only unblocks in this time fence.
    • The Replenish Shop Floor Warehouse (tiasc8210m000) session updates both before and in the Last Update Time Fence. If the update is the last update, the session also unblocks.
    • Whether an update by the Replenish Shop Floor Warehouse (tiasc8210m000) session is the last update, is defined by a comparison of line stations, and not by the relation to the last run of the current session or the Last Update Time Fence. Refer to one of the notes below for further explanation.
    • Messages can be updated, regardless if they are Blocked or not.
    • Messages can only be unblocked once.
Note
  • The previous explanation supposes that the Generate Time Fence is defined before the Frozen Time Fence, and the Frozen Time Fence before the Last Update Time Fence. In other words: the Generate Time Fence includes the Frozen Time Fence and the Frozen Time Fence includes the Last Update Time Fence.
  • The Replenish Shop Floor Warehouse (tiasc8210m000) session can generate, update and unblock supply messages. If it updates messages, it takes into account the Frozen Time Fence, but not the Last Update Time Fence. The last update, which also unblocks the messages, is performed when the line station in the Line Station Trigger From field in that session is the same as the Trigger-from Station that is defined in the Warehouse - Item (whwmd2110s000) session, for the assembly parts in the selected LSOs.
  • The session only generates messages for non-floor stock items. You define whether an item is floor stock in the Item - Warehousing (whwmd4100s000) session.
  • Do not confuse the Frozen Time Fence with the Freeze Time Fence that is defined in Line Assembly Configuration (LAC). The Freeze Time Fence in LAC has respect to the application of changes in the assembly line structure to the assembly orders.
  • The current session can only be used to generate and update SILS supply messages. The Replenish Shop Floor Warehouse (tiasc8210m000) session can also generate Batch supply messages. Once they are generated, Batch messages can not be updated, and they can also not be blocked.