This blog will cover ASRS Details in Warehouse.
The business strategy is to introduce the automated warehouse to increase the storage capacity at Warehouse and to automate a part of the pre-staging for shipments. The automated warehouse provides a good opportunity to increase the density of storage for those pallets which cannot be stacked on top of each other. The amount of load pre-staging done by the automated warehouse will be approximately one-third with two-thirds being done by the conventional warehouse.
The IT strategy is to use the existing SAP Warehouse Management system to control the movements into and out of the automated warehouse including which pallets are introduced, which loads are built and replenishment from the automated warehouse. Once the pallets are in the warehouse, the control will be by the WCS meaning that SAP WM will not control the positioning of pallets within the automated warehouse. All interfaces between SAP WM and WCS will be through the SAP MII server located on site in Warehouse XXX.
The WCS system will continue to run if the link to the SAP system is down with systems and processes in place to reconcile the data once the link to SAP becomes available.
SAP –> MII –>External Warehouse system & Vice versa.
1 Putaway into the ASRS
The ASRS is set up in SAP as Storage Type = 555. Control of which pallets should be sent to the ASRS and overall stock is done by SAP by messaging via idocs and webservices with the external Warehouse system.
1.1 Putaway Set-up
The selection of where to putaway from IBTs and Production is controlled by the Master Data set-up at SKU level. There are 2 controlling values which need to be set.:
1. The ZWCSSAP table contains the size of the virtual storage sections based on the logic of one bin per storage section.The total of the maximum bin quantities can be higher or lower than the physical ASRS capacity. This capacity will not be checked for bin to bin movements.
2. The bins have been created based on the Storage Section Indicator set in the Warehouse Mgmt 1 view of the Material Master. This allows the capacity to be controlled by product characteristics. Note that the bins are virtual bins and have no relation to where the pallets are physically stored within the ASRS.
3. The amount of material allowed into the bin is also controlled by the Maximum Bin Quantity as stored in the Warehouse Mgmt 2 view of the Material Master. This value can be changed using the MM02 transaction. It is very important to only use MM02 when changing data, if you wish to view the data use MM03 otherwise the data will be locked and no movement of the SKU will be possible.
The value in this field will not be checked for bin to bin movements and pallets introduced into the ASRS for direct despatch will not be included in the total.
4. Setting these 2 values correctly is the key to controlling the profile of stock within the ASRS. If you wish to block one SKU from going into the ASRS from production or IBT then set the Maximum bin quantity to 0. If you wish to block all product with the same characteristic from going into the ASRS then it is better to use a Putaway block on the bin linked to the section.
1.2 Putaway from production
The putaway from production process will check first whether there is space in the ASRS for all the pallets on the Forklift truck. The initial check is in SAP against the capacities set in section 1. If SAP decides to putaway to the ASRS then a webservice instant communication is sent to the External warehouse systems to check whether the ASRS can accept the pallets and which infeed they should be sent to.
If the response is positive then SAP will send the Transfer Orders to the WCS using the WMTORD idoc. The FLT driver will see the correct infeed on his VMU to take the pallets to. Once at the infeed the FLT driver will confirm the pallets and the Transfer Order will pass to the infeed queue. It’s important to note that the Transfer Order will not be confirmed at this point.
The External Warehouse System will profile the pallet and if it is accepted, a WMTOCO confirmation idoc will be sent to SAP to confirm the transfer order. If the pallet is rejected, the Transfer Order will stay open so that the FLT driver can either fix the problem or transfer the pallet to the rework area.
1.3 Putaway from IBT
The process for putaway from IBT is the similar to that for production with the difference that for IBTs the check is done pallet by pallet. This means that it is possible to have 2 pallets on a forklift truck with different destinations in conventional and ASRS. Use system guided putaway as usual to put these pallets at the correct infeed.
1.4 Putaway from a bin to bin move
LT10 can be used to move pallets from the conventional warehouse to the ASRS. See the later section for more detail on this.
1.5 Sending a pallet to Rework
If a pallet is rejected because it needs to be reworked, the process to cancel the putaway TO and create a new TO to the 810 – REWORK bin can be done from the VMU.
1. Scan the pallet with Non-System guided putaway
2. If the open TO is to an infeed, enter “REWORK” in the destination field then press Enter and F1-Save
3. Click YES to create the new TO
4. Press enter to accept the next message (it means that the putaway TO has been cancelled)
5. The TO will be created to REWORK and will can be found as an open TO to the REWORK area. Scan the pallet again using system guided putaway when in the REWORK destination and press F1 to confirm the TO.
1.6 Troubleshooting the putaway process
The process should work smoothly however on rare occasions the following events could happen.
i) Pallet is rejected because there is no TO from SAP – Check the SSCC code in SAP using HUMO or LT27 and find the transfer order. Check for this transfer order in the external Warehouse system event log, if it exists and is good then it’s probable that the idoc was delayed, in this case the pallet can be put back on the infeed and should be accepted (assuming the profile is ok).
ii) Pallet is expected to go to the ASRS but Tranfer Order is created to conventional warehouse – Assuming all the checks on the quantities for the material and storage section are checked, make sure that the ASRS bin does not have a putaway block. Check in the external warehouse system event log for rejected pre-advice, the external warehouse system will reject pallets if it is full or there are too many pallets already expected at the infeed.
One general thing to note is that full pallets can be taken to either infeed and confirmed but it is recommended to take the pallets to the infeed in the destination field on the TO as this is the one suggested by the external warehouse systems logic. This should only be ignored and the other infeed chosen if there are physical problems at one of the infeeds.
2 Despatch Tube set-up
The ASRS despatch tubes are set-up in SAP in storage type 916, as for conventional warehouse pre-assembly locations. The bins are numbered with a 2 digit sequence number followed by the ASRS bin number. This sequence number ensures that the work is spread between the ASRS tubes.
Each bin can be set-up as Shipments, Conventional/bin to bin or Replenishment. This is controlled using the storage section within the bin.
3 Picking from the ASRS
3.1 Selecting shipments for pre-assembly in the ASRS
The ASRS contains some of the pallets for the warehouse but the same products also exist in the conventional warehouse. As the FEFO (first expired first out) rule must be followed for customer orders (with the exception of old stock orders) then even a customer load for the same product could require a combination of pallets from the ASRS and conventional warehouses.
SAP will send a series of idocs to the external warehouse system at this point, one will be ZWCS_SHIPMENTS and this will contain a list of the Transfer Order numbers for the shipment along with the shipment time and other information. All of the Transfer Orders will also be sent as individual WMTORD idocs. At this point, the shipment will appear in the Advanced Shipment View of the external warehouse systems.
The picking will be done in reverse delivery order (i.e. last destination will be loaded first) and by sequencing the pallets by Dolly then Euro then Chep/DPB. The correct sequence must be followed so check this when looking for TOs that are available for picking.
The Transfer Orders could be from the ASRS to the pre-assembly tube (storage type 350 to 916), in this case the external warehouse system will decide which pallets to pick based on the FEFO strategy or batch if specified. These Transfer Orders will appear in the ASRS queue in LRF1/2. Once the pallet is picked and taken to the despatch tube, a WMTOCO idoc will be sent to SAP to confirm the Transfer Order with the SSCC code of the pallet.
Some Transfer Orders will be from the conventional warehouse to the ASRS despatch tube. These need to be fed into the ASRS infeed first and are treated like a normal conventional warehouse pre-assembly TO. When the pallet is picked from the conventional warehouse and confirmed to the ASRS, a webservice will be sent to the IWS to confirm the SSCC code for the transfer order. The external warehouse systems will profile the pallet at the infeed and take it to the despatch tube. The WMTOCO idoc to confirm the Transfer Order will be sent once the pallet is past the point of no return.
Once all the pallets are in the despatch tube, the shipment pre-staging is complete and the truck can be checked in for loading.
3.2 TO sequencing
Dispatch TOs are ordered by delivery and pallet type in the following way.
1. Dolly Pallets
2. Euro Pallets
3. Chep/DPB pallets
4. POD pallets
Where there is a mixture of pallets from ASRS and conventional of the same pallet type, the ASRS pallets must be confirmed into the ASRS despatch tube and the second TO created before the conventional pallets can be picked.
In the simplest example, for a single delivery Chep pallet shipment with pallets from both ASRS and conventional, these pallets must first be pre-assembled by the ASRS. Once this is complete, the pallets from conventional can be picked , followed by those from the ASRS.
In this example there are 3 pallets from the ASRS and 3 from conventional to be pre-assembled in conventional.
The ASRS picks the 3 pallets and the TOs are confirmed, new TOs are created in the pre-assembly queue.
The TOs from the conventional warehouse can now be picked.
The first 3 are bin to bin TOs and will create a shipment line in IWS with CON- as the start of the header. These TOs appear in the ASRS queue and will be picked by the ASRS. When the pallets are in the despatch tube, IWS will send a confirmation WMTOCO idoc and a new TO will be created from the ASRS despatch tube to the conventional pre-staging location.
The TOs will not be available to be picked by a FLT driver until the pallets from the ASRS are confirmed in the despatch tube.
Once the second TOs are created, these will appear in the PREASSEMBL queue along with the other TOs. In this example, the sequence is chep pallets for delivery 1 followed by dolly pallets then chep pallets for delivery 2 followed by dolly pallets. This is because system will require the pallets picked last to be loaded first to the truck.
3.3 Troubleshooting the shipment process
The process should work smoothly however it is a complicated process so there are a number of things to check if there are errors.
i) Pallets are showing as confirmed into the despatch lane in the External Warehouse system but not in SAP – check that the WMTOCO idoc has processed for all of the pallets. If there is an error, attempt to re-process using the BD87 transaction. This should fix the problem unless there is a genuine reason why the idoc cannot be processed. In these cases it may be necessary to take the SSCC code from External warehouse system and use it to manually confirm the TO in SAP, only do this if you are certain that the idoc cannot be re-processed.
ii) external warehouse system shows shortages on the shipment – This suggests a stock difference between external warehouse system and SAP. Find the Transfer Orders or SKUs missing stock in external warehouse system and check the stock levels in LX03 or equivalent SAP transaction. Identify in external warehouse system which pallets it cannot allocate and follow up on the history in SAP to identify the location of the pallets. These Transfer Orders will need to be cancelled and the pallets live-loaded to the shipment as the ASRS is unable to pick these. Note that shortages on pallets from the conventional warehouse just means that they have not been picked yet.
iii) ASRS error displayed on the VMU when taking pallets from conventional to the infeed – This normally happens if the external warehouse systems thinks that it already has the pallets. Check the SSCC codes in the external warehouse system Container Enquiry, if the pallets have a location (including Reject or Despatched) then they need to be deleted first from the external warehouse system. Do not do this if the pallets are in a storage location or on another shipment.
4 Cancelling Transfer Orders
TOs can be cancelled in SAP using LT15 but take care to understand the process for those TOs which involve pallets in transit to or from the ASRS.
When a TO is cancelled, a WMCATO idoc will be sent to the external warehouse system to request that the TO is cancelled. external warehouse systems will process the cancellation and send a WMCATO idoc back to SAP. When this idoc is processed, the TO will be cancelled. This is not an instant process and should take approximately a minute depending on the amount of idoc traffic at the time.
If after a few minutes the TO is not cancelled, check in WE05 or BD87 for any failed WMCATO inbound idocs. Check the reason for the failure and re-process the idoc. This should fix the problem unless there is a specific reason why the idoc cannot be cancelled.
If the TO is unknown in external warehouse system the reason needs to be investigated in external warehouse system. In these cases the subsystem items flag can be ticked to allow the cancellation. This is the only situation where the tick should be used as otherwise it will cause a mismatch between external warehouse system and SAP.
5 IDoc Monitoring
IDocs are data files that are being sent between SAP and the external warehouse system (Warehouse Control System). Normally the IDocs should work without problem in the background but there are circumstances which will cause them to fail, such as deliveries left in change mode and blocked bins. This document outlines how to identify and fix IDoc failures.
5.1 IDoc Structure
IDocs contain a Control Record and Data Segments, typically a header segment containing one or more item segments. Importantly IDocs always have a status which helpfully SAP indicates with a red (error), yellow (warning) or green (OK) indicator. The IDocs can be Outbound from SAP or Inbound to SAP.
5.2 IDoc Names
IDocs have both a message type and basic type so a WMTORD is also a WMTOID02, which can be confusing when entering search criteria. These are best viewed as the logical and technical names of an IDoc. So for example different versions of SAP may use the same Message Type but different Basic Types.
Transfer order creation
Transfer order confirmation
Cancel transfer order
shipment header (to warn WCS how many TOs to expect)
version of material master record IDoc
Move storage unit (handling unit / SSCC)