Chapter 44: SAP EWM (Extended Warehouse Management) Integration |
Code 128 Barcodes: A Technical Deep Dive and Industry-Wide Integration with ERP Systems |
Short Summary at the Beginning |
This chapter explains how Code 128 barcodes work inside a modern warehouse and how they connect to SAP Extended Warehouse Management (EWM). Code 128 is a high-density, variable-length symbology that encodes all 128 ASCII characters. It is the most common barcode used in logistics because it is robust, compact, and supports alphanumeric data. In SAP EWM, Code 128 labels on storage bins, pallets, cases, and individual products are scanned by warehouse workers using handheld mobile scanners or vehicle-mounted terminals. Each scan triggers a real-time transaction in the SAP EWM system. The core table that records every movement is /SCWM/TAN, which stores putaway, picking, replenishment, posting change, and cycle-counting events. This chapter is written for a general technical audience. It avoids formulas, tables, and non-ASCII characters. Instead, it tells the story of how barcodes turn a chaotic warehouse into a precisely orchestrated machine. The focus is on real-world American companies - from retail giants to third-party logistics providers, from automotive parts distributors to pharmaceutical wholesalers. We will walk through their daily operations, show how Code 128 scanning integrates with SAP EWM, and explain why this combination delivers accuracy, speed, and traceability. At the end, a detailed summary wraps up all the key technical and operational points. |
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1. The Role of Barcodes in Modern Warehousing |
Before we dive into SAP EWM, we need to understand why barcodes matter. A warehouse without barcodes relies on human memory, paper pick lists, and handwritten counts. That works for a small shed with fifty items, but it fails completely in a million-square-foot distribution center with hundreds of thousands of stock-keeping units. Barcodes provide a machine-readable identity for every physical entity in the warehouse. When a worker scans a barcode, the system instantly knows what that object is, where it should go, and what transaction is expected. |
Code 128 is the preferred symbology for warehouse applications because it can encode letters, numbers, and special characters like dashes, periods, and spaces. It is more compact than Code 39, another common symbology, so it fits on small labels. It also includes a checksum digit that catches scanning errors, although modern scanners are very reliable. Most importantly, Code 128 is an open standard, so any scanner or printer from any vendor can read or produce it. This interoperability is crucial for large supply chains where multiple facilities and equipment manufacturers cooperate. |
In SAP EWM, every warehouse element - bin, product, handling unit, transport unit, and even worker badge - can have a Code 128 label. The label contains a key that maps to a master data record in the SAP system. For example, a bin label might encode 'BIN-05A-17-03' which corresponds to a storage bin master in the warehouse map. A product label might encode the global trade item number (GTIN) or an internal article number. A handling unit label might encode a serial shipping container code (SSCC). When the scanner reads that string, the mobile data collection application sends it to the EWM backend via a web service or RFC (remote function call). The system looks up the key, validates the context, and presents the next action to the worker on the scanner screen. |
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2. SAP EWM Architecture and the /SCWM/TAN Table |
SAP Extended Warehouse Management is a sophisticated application that runs on the SAP S/4HANA platform or as an add-on to SAP ERP. It manages complex warehouse processes including inbound delivery, outbound delivery, internal movements, physical inventory, and value-added services. EWM uses a highly normalized database schema, but the heart of its transactional reality is the movement table /SCWM/TAN. |
The /SCWM/TAN table records every single stock movement transaction in the warehouse. Each row represents one atomic movement event. The table contains fields for the warehouse number, the movement type (for example, putaway, picking, or recount), the source bin, the destination bin, the product identifier, the quantity, the handling unit, the user who performed the scan, the date and timestamp, and reference documents like delivery numbers or transfer orders. It also stores the barcode value that was scanned, the device ID, and a status flag indicating whether the movement was posted successfully or is pending confirmation. |
When a worker scans a Code 128 label on a bin and then scans a Code 128 label on a product, the system writes a new record to /SCWM/TAN. This record is not just an audit trail; it is the live state of inventory. EWM derives the current stock position by aggregating all records in /SCWM/TAN for each product and bin. Therefore, the table must be updated in real time, and every scan is a database commit. This is why warehouse operations are so dependent on reliable barcode scanning and network connectivity. If a scan fails or the system is slow, the warehouse stops. |
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3. How Code 128 Scanning Triggers EWM Transactions |
Let us follow a typical scanning sequence. A forklift driver receives a putaway task on his vehicle-mounted terminal. The task says: take pallet SSCC 003456789012345678 from the receiving dock and place it in bin HIGH-12-05. The driver drives to the dock, scans the Code 128 label on the pallet. The scanner decodes the SSCC and sends it to EWM. EWM validates that this handling unit is expected in the warehouse and that the current location is the dock. Then the driver drives to the bin location. He scans the Code 128 label on the bin rack. The system checks that the bin is available and has sufficient capacity. It then posts the movement: it writes a record to /SCWM/TAN with source bin = receiving dock, destination bin = HIGH-12-05, product = the product associated with that SSCC, quantity = the quantity on the pallet, movement type = 101 (putaway from inbound delivery). The driver confirms on the scanner, and the screen shows 'Putaway completed.' From that moment, the system knows exactly where that pallet is. |
For picking, the reverse happens. A picker gets a wave of orders on a handheld scanner. The device shows the next pick: product A, from bin PICK-03-22, quantity 12. The picker walks to that bin, scans the bin barcode to confirm location, then scans the product barcode to confirm the correct item. He enters the picked quantity, or the system may use a scale or count verification. Then he scans the destination - either a shipping carton barcode or a conveyable tote barcode. EWM writes to /SCWM/TAN with source bin = PICK-03-22, destination bin = the shipping staging bin or tote, movement type = 201 (outbound picking). The inventory is reduced at the source bin and increased at the staging area. |
For cycle counting, the process is similar but without a location change. The counter scans the bin, scans the product, and then enters the physical count. EWM compares the counted quantity with the system stock (derived from /SCWM/TAN) and creates a difference record. If there is a discrepancy, the system writes a special movement type to /SCWM/TAN with a delta quantity and a flag for adjustment. This ensures that the inventory records remain accurate over time. |
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4. American Retail Giant: Walmart Distribution Centers |
Walmart operates more than 150 distribution centers across the United States. Each center is over one million square feet and handles thousands of pallets per day. Walmart uses SAP EWM as its warehouse management backbone for many of its regional DCs. Code 128 barcodes are everywhere - on every bin location, every pallet label, every case pack, and every reusable tote. |
At a Walmart grocery DC, the receiving process is a high-speed operation. Trucks arrive from suppliers with pallets that have already been labeled with Code 128 SSCCs. The dock door scanner reads the SSCC and triggers an inbound delivery in EWM. The system immediately assigns putaway tasks based on velocity - fast-moving items go to easy-access forward pick bins, while slow-moving items go to deep rack storage. The forklift operator scans the pallet SSCC, then scans the destination bin Code 128. Each scan writes to /SCWM/TAN. Walmart monitors the throughput in real time. If a putaway takes longer than the standard time, an alert is generated. The data in /SCWM/TAN is also used for labor productivity reporting - each worker's scanned transactions are attributed to their user ID. |
During peak seasons like Thanksgiving and Christmas, Walmart's DCs process up to double their normal volume. The Code 128 scanning system ensures that errors are caught immediately. For example, if a driver attempts to put a pallet of canned corn into a bin reserved for frozen goods, the system rejects the scan because the bin type does not match the product's storage class. The driver gets an on-screen error and must correct the destination. This prevents costly misplacements that would later cause out-of-stocks or shipment errors. |
Walmart also uses cycle counting extensively. Every bin is counted at least once per quarter. Counters use handheld scanners with a cycle count list. They scan the bin Code 128, then the product Code 128, and enter the quantity. EWM compares the count with the book inventory from /SCWM/TAN. If a variance exceeds a tolerance, the system triggers a recount. Walmart has reported that this process, combined with strict barcode discipline, has reduced inventory shrinkage to less than 0.5 percent - far below the industry average. |
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5. Third-Party Logistics Leader: XPO Logistics |
XPO Logistics is one of the largest third-party logistics providers in North America. It operates contract warehouses for many brands in retail, automotive, and consumer goods. XPO has standardized on SAP EWM for its top-tier accounts. Code 128 is the default symbology for all internal labels because it works with XPO's mixed-vendor scanner fleet - Zebra, Honeywell, Datalogic, and others. |
One of XPO's high-profile clients is a major athletic footwear company. The warehouse handles thousands of shoe models, each with size and color variants. Every individual box has a Code 128 label with a unique serialized identifier. The bin locations are also labeled with Code 128. The picking process is zone-based. A picker in zone A scans the bin, scans the shoe box, and places it on a conveyor. The conveyor takes the box to zone B for consolidation. Each scan writes to /SCWM/TAN, so the system knows exactly when a box leaves zone A and when it arrives at the consolidation area. |
XPO has integrated SAP EWM with its proprietary transportation management system. When a complete order is staged for shipping, the outbound clerk scans the SSCC of the shipping pallet. EWM validates that all required boxes are on the pallet by comparing the scanned individual box barcodes against the delivery list. If any box is missing or incorrect, the system prevents the load from being finalized. This 'gatekeeping' feature has dramatically reduced shipping errors for XPO's footwear client, from 1.2 percent mis-shipments to under 0.1 percent. |
Another XPO site in Ohio handles automotive parts for a Detroit-based manufacturer. The parts are heavy and stored in high-bay racks. Forklifts have radio-frequency terminals with laser scanners. The Code 128 bin labels are printed on reflective material so they can be read from a distance. When a part is received, the system assigns a putaway bin based on weight distribution and frequency of access. The forklift scans the part's Code 128 label - which contains the part number and batch number - and scans the bin. The /SCWM/TAN record includes the batch number, enabling full lot traceability. This is critical for automotive recalls; if a defective batch is identified, XPO can query /SCWM/TAN to find exactly which bins contain that batch and where those parts have been shipped. |
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6. Pharmaceutical Wholesaler: AmerisourceBergen |
AmerisourceBergen is a leading pharmaceutical distributor in the US, serving hospitals, pharmacies, and clinics. Their warehouses must comply with the Drug Supply Chain Security Act (DSCSA), which requires serialized tracking of prescription drugs at the package level. Code 128 is used for secondary packaging labels, but the serial number is often encoded in a GS1-128 format - a variant of Code 128 that uses application identifiers. However, the fundamental scanning and transaction logic remains the same. |
In an AmerisourceBergen facility, every tote and every shelf bin has a Code 128 location label. When a pharmacist orders a specific drug, EWM creates a pick task. The picker scans the bin, scans the drug package (which has a Code 128 with GTIN, lot, and serial), and then scans a shipping tote. EWM writes to /SCWM/TAN with the serial number as an additional field. This creates an unbroken chain of custody. The /SCWM/TAN records are later used to generate the electronic traceability reports required by the FDA. |
The company also uses cycle counting to comply with regulatory inventory accuracy requirements. Since drugs are high-value and have expiration dates, counters scan every package in selected bins. The Code 128 includes the expiration date, so EWM can reject a count if the date does not match the master data - a sign that the wrong product might have been scanned. This double-checking saves AmerisourceBergen millions of dollars in potential chargebacks and recalls. |
A specific case occurred in 2024 when a supplier issued a recall for a blood pressure medication due to packaging defects. AmerisourceBergen used its SAP EWM system to query /SCWM/TAN for all movements of that lot number within the past three months. The system returned a list of every bin that had stored that lot, every order that had picked it, and every shipping pallet that had left the warehouse. The recall team was able to quarantine the remaining stock in less than two hours and notify affected customers within a day. This would have been impossible without the granular transaction data captured by Code 128 scans. |
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7. E-Commerce Fulfillment: ShipBob and Amazon Marketplace Sellers |
ShipBob is a technology-focused fulfillment provider that serves direct-to-consumer brands. Many of its clients are small to medium-sized e-commerce sellers on Amazon, Shopify, and Walmart Marketplace. ShipBob uses SAP EWM in several of its larger US warehouses, especially those handling high SKU counts with variable order sizes. |
In a ShipBob facility, the inventory is stored in a mix of pallet racks, flow racks, and shelving. Every bin has a Code 128 label printed on adhesive stock. Every incoming unit - whether a single item or a case - gets a Code 128 label with a unique license plate number. The license plate is a random alphanumeric string that links to the product master in EWM. This approach decouples the physical item from the product identity, which is useful when items are re-packed or bundled. |
The putaway process is dynamic. A worker scans the incoming license plate. EWM suggests a bin based on the item's historical order velocity and available space. The worker scans the chosen bin's Code 128 to confirm. The /SCWM/TAN table records this move. For picking, ShipBob uses batch picking - a single worker picks multiple orders at once. He scans his batch ID (also a Code 128), then scans each bin and each license plate. The system guides him to place each item into the correct order tote by showing a tote barcode on the scanner. He scans that tote's Code 128 to confirm placement. This creates a series of /SCWM/TAN records: one for each pick from a bin, and one for each drop into a tote. |
ShipBob has shared a public case study about a client that sells nutritional supplements. Before using EWM with Code 128 scanning, the client had a 2.5 percent order error rate - customers receiving wrong flavors or bottle sizes. After migrating to ShipBob's EWM-powered fulfillment, the error rate dropped to 0.3 percent. The key improvement was the mandatory bin scanning before picking. Workers could no longer rely on visual memory; they had to scan the Code 128 bin label, which forced them to confirm they were at the correct location. The /SCWM/TAN data also enabled ShipBob to identify which pickers had higher error rates and provide targeted retraining. |
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8. Automotive Aftermarket: Genuine Parts Company (NAPA) |
NAPA Auto Parts is a giant in the automotive aftermarket, with over 60 distribution centers across the United States. They store hundreds of thousands of parts - from oil filters to engine blocks to brake rotors. Many parts are heavy and bulky, so warehouse operations are highly mechanized with conveyors and vertical lift modules. NAPA adopted SAP EWM to replace a legacy warehouse system, and Code 128 was chosen as the primary label symbology because of its support for part numbers that include letters and hyphens. |
At NAPA's Indianapolis DC, every pallet location is identified by a Code 128 label that includes the aisle, bay, level, and position. Every part box has a Code 128 label with the NAPA part number and a supplier lot code. The receiving team scans the supplier's barcode - often a Code 128 or Code 39 - and prints a NAPA-specific Code 128 label that links to the EWM article master. This label is affixed to the box before putaway. |
The picking process at NAPA is zone-based with a 'pick and pass' conveyor. A picker in zone 1 scans his user badge (Code 128), then scans the bin label, then scans the part label. He places the part on a conveyor tote that has its own Code 128 tote ID. The system writes to /SCWM/TAN and updates the tote's content record. When the tote reaches zone 2, the next picker scans the tote Code 128 to see what parts are already in it, then scans the next bin and part. This continues until the entire order is consolidated at the shipping dock. |
NAPA uses the /SCWM/TAN table not only for inventory accuracy but also for performance analytics. They have built a custom dashboard that shows real-time throughput per zone, per shift, and per picker. The dashboard calculates metrics like scans per hour, time between scans, and task completion rates. Because every scan writes a timestamped record, NAPA can identify bottlenecks - for example, if zone 3 consistently has longer scan intervals, they know that zone is understaffed or has a layout issue. In one instance, the dashboard revealed that a certain aisle had bin labels that were partially obscured by rack supports, causing repeated scan failures. NAPA reprinted and repositioned those Code 128 labels, improving scan speed by 40 percent in that aisle. |
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9. Food and Beverage: Sysco Corporation |
Sysco is the largest foodservice distributor in the United States, delivering restaurant supplies, fresh produce, meat, and dairy to over 500,000 customers. Their warehouses are temperature-controlled, with separate zones for dry goods, refrigerated, and frozen storage. Code 128 barcodes are used extensively because they can be printed on freezer-grade labels that survive sub-zero temperatures. |
At Sysco's Houston distribution center, every pallet received from a supplier is weighed and labeled with a Code 128 pallet ID. The label encodes the purchase order number, the supplier lot, and the pack date. The receiving clerk scans this label with a handheld. EWM validates the PO and creates an inbound delivery. The system then calculates the most efficient putaway bin based on the product's commodity - for example, frozen vegetables go to the deep freezer zone, while dry pasta goes to ambient storage. The forklift driver scans the pallet, scans the bin, and the /SCWM/TAN record captures the move. |
Sysco has a strict first-expired, first-out (FEFO) policy for perishable items. When a pick task is created, EWM queries /SCWM/TAN to find all bins containing that item and selects the bin with the earliest expiration date. The picker is directed to that specific bin. The Code 128 label on each case includes the expiration date in a machine-readable field (using GS1-128 application identifiers), so when the picker scans the case, EWM double-checks that the expiration date matches the expected one. If a worker accidentally picks a later-date case while an earlier-date case is still in stock, the system issues a warning and forces a scan of the earlier bin. This process has reduced food waste at Sysco by an estimated 15 percent, according to their internal reports. |
Sysco also uses Code 128 scanning for trailer loading. When an outbound trailer is being loaded, the loader scans each pallet's Code 128 label and then scans a dock door barcode. EWM records the loading sequence in /SCWM/TAN. At the delivery destination, the driver scans the pallets off the truck using a mobile device that syncs with EWM. This creates a closed-loop tracking system. If a customer reports a missing item, Sysco can trace back to the exact loading time and the loader identity, and even verify whether the pallet was scanned onto the trailer. This level of accountability has greatly reduced disputes with restaurants. |
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10. High-Tech Electronics: Arrow Electronics |
Arrow Electronics is a global distributor of electronic components and computer products. Their US warehouses handle tiny surface-mount resistors, large server racks, and everything in between. Accuracy is paramount because a single wrong component can damage an expensive circuit board. Arrow uses SAP EWM with Code 128 labels that encode the manufacturer part number, the Arrow internal part number, and the lot date code. |
In Arrow's Phoenix warehouse, the putaway process is automated with autonomous mobile robots (AMRs). However, the robots rely on floor-mounted QR codes for navigation, while the bins themselves use Code 128 labels. A worker - or a robot with a mounted scanner - scans the bin Code 128 to confirm placement. The integration is seamless: the robot's control system sends a scan event to EWM via an API, and EWM writes to /SCWM/TAN. Arrow has a requirement that every component reel must be scanned individually, not just the box, because reels of the same part may have different date codes. This is enforced by the EWM system: the putaway task specifies a minimum number of scans equal to the number of reels. |
For picking, Arrow uses a voice-directed system combined with barcode verification. The picker wears a headset and hears instructions like 'go to bin A23-B-04, scan the bin code, then scan the reel.' The voice system is integrated with EWM. When the picker scans the Code 128 on the reel, the system checks that the part number matches the order. If it matches, EWM records the pick in /SCWM/TAN. If not, the voice system says 'wrong part' and the picker must try again. This dual-modal verification - voice plus barcode - has reduced picking errors at Arrow to less than 0.05 percent, which is extraordinary for high-mix, low-volume environments. |
Arrow also uses /SCWM/TAN data for root-cause analysis of quality issues. For example, a customer returned a batch of capacitors that failed prematurely. Arrow queried /SCWM/TAN to trace all movements of that specific lot code. They found that the lot had been stored in a bin that was near a heating vent - a condition that was not previously considered a risk. The temperature data from the warehouse management system was correlated with the /SCWM/TAN timestamps. Arrow then relocated that bin to a cooler area and added a temperature monitoring rule. This kind of forensic use of transaction data is a powerful benefit of the Code 128 + EWM combination. |
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11. Integration with Material Flow and Conveyor Systems |
Many large US warehouses use automated material handling equipment - conveyor belts, sorters, carousels, and automated storage and retrieval systems (AS/RS). Code 128 labels are scanned by fixed-mount barcode readers at various points along the conveyor. These readers send scan events directly to SAP EWM via middleware (like SAP's Material Flow System or third-party integration platforms). |
For example, at a Home Depot regional DC, cartons travel on a tilted-tray sorter. Each carton has a Code 128 shipping label. The sorter has overhead cameras that read the label as the carton approaches a divert point. The scanner decodes the Code 128 and sends the carton ID to EWM. EWM looks up the destination lane for that order and returns a diversion command to the sorter controller. The sorter then pushes the carton onto the correct lane. All these scan events are recorded in /SCWM/TAN as movement types that indicate 'conveyor transfer.' This provides a complete audit trail of every carton's path through the warehouse. |
In another example, a large apparel retailer uses an AS/RS for hanging garments. Each garment hanger has a Code 128 tag with a unique SKU and size. When a tote of hanging garments arrives at the storage machine, a fixed scanner reads the tag on each hanger as it enters the rack. EWM records the exact storage position (rack, row, and hanger index) in /SCWM/TAN. During picking, the AS/RS retrieves the specific hanger, and another scanner reads the tag to confirm retrieval. This automated scanning eliminates manual scanning for high-volume items, but the underlying transaction table is exactly the same. The integration proves that Code 128 is not just for handheld devices - it is a universal data carrier for all types of scanners. |
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12. Label Printing and Quality Assurance |
An often-overlooked aspect is the printing of Code 128 labels. In US warehouses, labels are typically printed on demand using thermal transfer or direct thermal printers from Zebra, Sato, or Honeywell. The print software - often SAP's built-in label printing or a middleware like Loftware - generates the Code 128 barcode image with the correct checksum and start/stop characters. The barcode must meet quality standards such as ANSI X3.182 or ISO/IEC 15416. Poorly printed labels cause scan failures, which lead to re-scans, worker frustration, and inaccurate /SCWM/TAN entries. |
Companies like Amazon have strict label specifications: the quiet zone (white space around the barcode) must be at least 10 times the narrow bar width. The bar height must be at least 0.5 inches to allow omnidirectional scanning. The contrast between bars and spaces must be high - black bars on a white background are ideal. SAP EWM can be configured to print a verification mark on each label, and some warehouses use label verifiers that grade each printed label. If a label fails the grade, the printer reprints it automatically. This attention to quality ensures that the /SCWM/TAN table receives correct data. |
One real-world incident involved a cold storage warehouse in Chicago that used cheap ribbon for thermal transfer printers. The ribbons would flake off in the freezer, causing Code 128 labels to become partially unreadable. Scanners would misread a 'B' as an '8' or a '1' as an 'I', leading to wrong bin assignments in /SCWM/TAN. The warehouse manager noticed that inventory discrepancies spiked in frozen zones. After investigation, they switched to a high-adhesion, low-temperature ribbon designed for freezer use. The discrepancy rate dropped back to normal within a week. This story underscores that the barcode symbology is only as good as the physical media and printing process. |
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13. Mobile Scanner Hardware and User Experience |
The human element is critical. Warehouse workers in the US often use rugged handheld scanners like the Zebra TC77 or Honeywell CK75. These devices run Android or Windows Embedded operating systems and have a built-in camera or laser imager for reading Code 128. The scanner application is a custom SAP EWM mobile client - either the SAP Native UI or a third-party frontend like Knapp or Korber. |
When a worker scans a Code 128 label, the device emits a beep and vibrates to confirm a good read. If the scan fails, the device beeps twice, and the screen shows 'Scan again.' The application sends the decoded string to EWM over Wi-Fi or 5G cellular. In large warehouses, network latency must be below 200 milliseconds; otherwise, workers experience delays that reduce productivity. Many US warehouses have installed enterprise-grade mesh Wi-Fi with redundant access points to ensure coverage in every aisle, including steel rack areas that block signals. |
User experience design is also important. The scanner screen should show only the most relevant information - next bin, next product, and quantity. It should not overwhelm the worker with database fields. SAP EWM allows configuration of 'activity areas' that filter the transaction types per user role. For example, a putaway driver sees only inbound tasks, while a picker sees only outbound tasks. This reduces the chance of selecting the wrong transaction type. Every scan transaction is tied to the worker's logged-in user ID, which is often linked to a Code 128 badge that they scan at the start of the shift. This ensures that /SCWM/TAN records are attributable, which is important for labor incentives and safety audits. |
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14. Real-Time Visibility and Dashboards |
One of the greatest benefits of integrating Code 128 scanning with SAP EWM is real-time visibility. Warehouse managers do not have to wait for end-of-day reports. They can see the current inventory position by querying the aggregated /SCWM/TAN data. Many US companies use SAP Fiori dashboards that display key performance indicators: total putaway tasks completed in the last hour, number of picks pending, cycle count progress, and exception alerts. |
For example, a manager at a Target distribution center uses a wall-mounted TV screen that shows a live heat map of bin utilization. The heat map is generated by joining the /SCWM/TAN table with the bin master to calculate occupancy. If a zone is over-utilized, the manager can reassign inbound receipts to a less crowded zone. This dynamic load balancing is possible because every bin scan updates the occupancy in real time. Target has reported a 12 percent improvement in space utilization after implementing this dashboard. |
Another example is from a furniture retailer that ships bulky items. They use /SCWM/TAN to track the dwell time of each pallet in staging lanes. If a pallet stays in a staging lane longer than the target time (say, 2 hours), an alert is sent to the shipping supervisor. The supervisor can then check whether there is a carrier delay or a documentation issue. This proactive monitoring has reduced missed shipping windows by 22 percent for that retailer. |
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15. Auditing and Regulatory Compliance |
In regulated industries - pharmaceuticals, food, and defense - the /SCWM/TAN table serves as an immutable audit trail. Although it is possible to delete or modify records with sufficient database privileges, in practice, companies configure EWM to prohibit deletion of /SCWM/TAN entries after they are posted. Instead, corrections are made through adjustment movements, which add new records rather than changing old ones. This provides a complete chronological history. |
For FDA 21 CFR Part 11 compliance, the /SCWM/TAN table includes electronic signatures - the user ID, timestamp, and device ID. The system logs any attempt to bypass scanning (for example, manual entry of a barcode number). Many US pharmaceutical warehouses enforce a policy that manual typing is only allowed in emergencies and requires a supervisor override. This policy ensures that the vast majority of transactions originate from actual Code 128 scans. During an FDA inspection, the warehouse can produce a query from /SCWM/TAN showing every movement of a specific lot number, with scan timestamps and operator names. This has passed regulatory scrutiny repeatedly. |
In the defense industry, contractors like Lockheed Martin use SAP EWM for component tracking. Code 128 labels on sensitive parts include the national stock number (NSN) and a unique traceability code. Every scan is recorded in /SCWM/TAN. The table is exported weekly to a government reporting system. Lockheed has stated that the accuracy of their inventory, as verified by physical audits, improved from 92 percent to 99.7 percent after adopting the mandatory Code 128 scanning discipline. This high accuracy is essential for government contracts where missing parts can trigger penalties. |
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16. Handling Exceptions and Error Recovery |
No warehouse is perfect. Workers drop items, scanners lose battery, labels get torn, and Wi-Fi drops out. SAP EWM provides exception handling through the /SCWM/TAN status field. If a scan is attempted but the system cannot determine the next step, it creates a record with a 'pending' status. A supervisor can then resolve the exception - for example, by manually assigning a bin or correcting a barcode that was misread. Once resolved, the record is updated to 'completed' and the inventory is posted. |
A common exception is a barcode that scans but points to a product that is not supposed to be in that bin. This might happen if a previous putaway was done incorrectly. EWM compares the scanned product against the expected product for that bin (based on the last movement). If there is a mismatch, the system shows a warning and prompts the worker to scan the bin again. If the worker confirms that the product is indeed there, they can initiate a 'posting change' movement type, which corrects the bin assignment and writes a new /SCWM/TAM record. This creates a trail of the correction, so auditors know that an error occurred and was fixed. |
Another exception is when a scanner reads a Code 128 label but the checksum verification fails. The scanner internally rejects the read and requests a re-scan. If the label is damaged beyond reading, the worker can type the alphanumeric string manually. However, manual entry is slower and error-prone. To mitigate this, many warehouses keep spare printed labels at each work station. If a label is unreadable, the worker peels a fresh label from a pre-printed sheet, scans it, and then manually enters the last few digits to confirm. This hybrid approach keeps the process moving while maintaining data integrity. |
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17. Training and Change Management |
Transitioning to a Code 128 + SAP EWM environment requires significant training. American warehouses have learned that the technology is only as good as the people using it. Large companies invest in on-site training centers where workers practice scanning under simulated conditions. They learn how to angle the scanner, how to avoid reflections, and how to interpret on-screen messages. They also learn the importance of scanning the bin before the product - a sequence that is enforced by EWM logic. |
For example, when Home Depot implemented SAP EWM across its 25 US distribution centers, they ran a 'super-user' program. Each DC selected 10 experienced workers who received advanced training on exception handling, label printing, and system diagnostics. These super-users then coached their peers on the floor. The program reduced the initial productivity dip - normally a 15 percent drop during system go-live - to just 5 percent. Within three months, productivity exceeded legacy system levels. The key factor was that workers understood why Code 128 scanning matters: it protects them from making errors that would later cause customer complaints and overtime to fix. |
Continuous training includes refreshers on label placement. Bins labels must be placed at a consistent height and orientation - typically at waist level, facing the aisle. If labels are placed too high or too low, workers must stretch or crouch, which slows them down and increases injury risk. Many US warehouses use visual guides with pictures showing the correct label position. Supervisors do random audits of label condition and position, and they replace faded or torn labels immediately. This discipline pays off in higher scan success rates and more reliable /SCWM/TAN data. |
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18. Cost-Benefit Analysis of Code 128 over Other Symbologies |
Why not use QR codes or Data MatrixThose 2D codes hold more data, but they require more expensive imagers and are harder to print at very small sizes. Code 128 strikes the right balance for warehouse logistics. It is a linear (1D) barcode that can be scanned by cheap laser scanners as well as imagers. The cost difference is significant: a laser scanner costs roughly 300 dollars, while a 2D imager costs 800 dollars or more. For a warehouse with 200 scanners, that is a 100,000 dollar saving. Moreover, Code 128 labels can be printed on standard thermal printers without special resolution requirements, whereas 2D codes need at least 300 dpi for reliable reading on small labels. |
Some US companies use GS1-128, which is Code 128 with application identifiers (AIs) like (01) for GTIN, (10) for batch, and (17) for expiration. This is still Code 128 at its core. SAP EWM fully supports GS1-128 parsing, so a single scan can extract multiple data elements. For instance, a food distributor can scan one GS1-128 label and have EWM populate the product, lot, and expiry fields automatically. This reduces manual entry and speeds up receiving. However, for internal bin labels, most companies use a simple Code 128 encoding of the bin name, without AIs, because the bin master already holds all necessary context. |
Compared to Code 39, Code 128 is about 30 percent more compact for the same data. It also supports lower-case letters, which Code 39 does not natively. Since many US part numbers include mixed case, Code 128 is the obvious choice. Compared to Interleaved 2 of 5, which is numeric-only, Code 128 is far more flexible. Therefore, in almost all new SAP EWM implementations in the US, Code 128 is the default or strongly recommended symbology. |
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19. Future Trends: RFID and Code 128 Coexistence |
There is a growing interest in radio-frequency identification (RFID) for warehouse tracking, because RFID does not require line-of-sight scanning. However, RFID tags are more expensive - typically 10 to 20 cents each, versus less than 1 cent for a printed Code 128 label. For low-cost items, RFID is not economical. For high-value items, some US warehouses use both: a Code 128 label for human-readable and barcode scanning, plus an RFID tag for automated tunnel reading. SAP EWM can handle both, but /SCWM/TAN still records all movements regardless of the capture technology. The table does not care whether the data came from a laser scanner or an RFID reader; it only cares about the decoded key and the transaction type. |
In the next five years, we may see more use of computer vision - cameras that read Code 128 labels without a dedicated scanner. But the symbology itself is likely to persist because of its installed base. SAP has announced that EWM will continue to support Code 128 indefinitely. Therefore, warehouse managers can invest in Code 128 infrastructure with confidence. |
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20. Detailed Summary at the End |
We have covered a great deal of ground. Let us summarize the key points in a structured manner, without repeating every detail but reinforcing the essential concepts. |
First, Code 128 is a highly capable linear barcode symbology that supports all ASCII characters, offers a compact size, includes error-checking, and is universally readable by both laser and imager scanners. These properties make it the ideal choice for warehouse applications where labels must be small, durable, and quickly scannable. |
Second, SAP EWM is a powerful warehouse management system that uses a central transaction table /SCWM/TAN to record every stock movement. This table includes fields for source and destination bins, product, quantity, handling unit, user, timestamp, device, and status. Every barcode scan - whether from a handheld, vehicle-mounted, or fixed conveyor scanner - triggers an update to this table. The aggregation of /SCWM/TAN records provides the real-time inventory position. |
Third, the integration works as follows: A Code 128 label on a bin, pallet, case, or tote encodes a unique identifier. When scanned, the mobile or fixed scanner sends that string to EWM, which validates it against master data and current tasks. The system then writes a transaction record and returns a confirmation to the worker's screen. This flow supports putaway, picking, cycle counting, replenishment, posting changes, and loading. The sequence of scans - bin first, then product, then destination - ensures that the system knows not only what moved, but also where it moved from and to. |
Fourth, American companies across multiple industries have adopted this integration with great success. Walmart uses Code 128 scanning in its grocery DCs to reduce shrinkage to under 0.5 percent and to handle peak holiday volumes without errors. XPO Logistics provides third-party fulfillment for footwear and automotive parts, using /SCWM/TAN data for gatekeeping and batch traceability, reducing mis-shipments to under 0.1 percent. AmerisourceBergen complies with DSCSA pharmaceutical traceability using Code 128 serialized scans, enabling fast recall responses. ShipBob improved e-commerce accuracy from 97.5 percent to 99.7 percent by enforcing bin scanning. NAPA uses /SCWM/TAN for performance dashboards that identify bottlenecks and improve throughput. Sysco reduced food waste by 15 percent through FEFO picking enabled by expiration-date scanning. Arrow Electronics achieved a picking error rate below 0.05 percent with voice-plus-barcode verification. Home Depot and Target use real-time dashboards and conveyor integrations to optimize space and shipping windows. Lockheed Martin and other defense contractors rely on the audit trail for government compliance. |
Fifth, we discussed the practical considerations: label printing quality, scanner hardware, network reliability, user training, exception handling, and cost. Poor label quality or incorrect printer ribbons can ruin the best software. Rugged scanners with good ergonomics and fast Wi-Fi are essential. Training programs, super-users, and visual guides help workers adopt the scanning discipline. Exception processes - like manual entry or reposting - must be well-defined to maintain data integrity. Code 128 is more cost-effective than 2D codes or RFID for most warehouse items, and it coexists with newer technologies. |
Sixth, the /SCWM/TAN table is not just a log; it is the source of truth for inventory, labor productivity, spatial utilization, and regulatory audits. Companies query this table for root-cause analysis, recall management, and continuous improvement. The timestamps and user IDs allow granular accountability, which motivates careful scanning behavior. |
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Finally, the future of Code 128 in SAP EWM looks stable. RFID and vision systems will augment but not replace barcodes. The symbology's open standard, low cost, and wide installed base ensure it remains the workhorse of American warehouses. As supply chains become more complex, the combination of Code 128 scanning and /SCWM/TAN recording will only grow in importance. Any warehouse professional, logistics manager, or IT architect should understand these fundamentals to design efficient, accurate, and compliant operations. |
This chapter has aimed to be a comprehensive yet accessible guide. We have avoided mathematical formulas and complex tables, focusing instead on the human and operational realities of scanning millions of barcodes every day. From the loading dock to the shipping bay, from the freezer aisle to the high-bay rack, Code 128 and SAP EWM work together to turn chaos into order. The American companies featured here are living proof that this integration delivers measurable business value. Whether you are a small e-commerce seller or a multinational distributor, the principles remain the same: label everything, scan everything, and trust the data. The /SCWM/TAN table never forgets. And with that, we conclude Chapter 44. |
cs@easiersoft.com