Bar coding for inventory and warehousing applications has been around for quite awhile. Viewed in the simplest manner, a warehouse must receive, inventory, and ship product efficiently. When mistakes are made in the warehouse, problems are often compounded before they are corrected. For example, if an item is incorrectly pulled from stock, not only would inventory be off, but the mistake of shipping the incorrect item would cause customer dissatisfaction, increased shipping and overhead costs, additional man-hours to "adjust" the problem, etc. Automatic ID has been a driving force in improving Inventory Control operations. Many affordable solutions now exist and can be implemented to improve productivity and reduce errors in what has historically been marketed only to Fortune 500 companies.
Whether a company is small or one of the Fortune 500, Inventory Control is not an option, it's a must. In today's competitive market, with smaller profit margins, inventory levels must accurately be maintained. Solutions exists starting from integrating a simple wedge decoder to more complex RF data collection systems. Most companies already have inventory applications currently installed. While some of these applications can be improved, the focus of this section is to provide a more efficient way of getting to and updating the host information.
To begin with, when the inventory is received, each product must be properly labelled. Most off-the-shelf programs can accommodate any kind of label. The label itself can practically be any material including paper, vinyl, polypropylene, or polyester. These are the most common face stocks available (for additional information, see the Ribbons and Labels section). Paper is the most common face stock and the least expensive. If the label must be smudge or smear resistant and/or hundreds or thousands of labels will be created daily, it is probably best to use a thermal transfer or direct thermal printer. Otherwise, a common office dot matrix or laser printer is sufficient to print labels.
The label must include a printed bar code. For most inventory applications Code 39 or Code 128 is adequate. The part number which is usually bar coded and a description of the part are often the minimum contents on the label. The time and date can also be added. Once the items are labelled, there are many solutions to maintain an accurate inventory.
If the warehouse is relatively small, the items for an order can be verified with a simple scanner and wedge decoder setup. The items must be physically brought to a terminal station. In a small warehouse, this is the least expensive approach to begin implementing bar codes for Inventory Control. Extenders can be added to some wedge decoders to have wireless scanning capability of up to 100 feet. If the warehouse is more than 30,000 sq. ft. Radio Frequency (RF) should be considered.
RF solutions provide real-time access to a central database in which the on-hand, committed, and on-order values are kept for each item. Radio Frequency Data Collection (RFDC) eliminates the inefficiency of an individual walking back-and-forth to a host terminal to query the database. As previously mentioned, there are now affordable RFDC systems that can be installed in practically any warehouse environment. With this configuration, the worker generally scans the item at the bin location for one of several reasons (1) to determine if it is the correct item, (2) to directly update the host database, (3) to locate additional inventory, and (4) to immediately update and flag any discrepancies for unexpected stock outages. RFDC is certainly a remarkable technology for inventory control.
If RFDC is cost prohibitive and/or real-time access to the host computer is not necessary, batch Portable Data Terminals (PDT) are an alternative.
Several clever methods can be employed with PDTs to simulate real-time access with a host computer by loading the database onto the portable reader. If this is coded in C or PASCAL, this will generally require several weeks of development time to get an initial program working. The key though is that simulated configurations are not real-time. The user must still manually upload the information at a workstation. With decreasing prices and today's technology, RFDC should be considered first if real-time access in necessary. Most PDTs have resident operating programs and can easily be programmed to record inventory. Applications can be written to prompt the user to input certain fields such as the item number and quantity. Additional fields can prompt for the warehouse number, aisle, bin, and shelf. When the operator has completed the set of tasks, the PDT is connected to a host terminal so that the inventory file can be uploaded. For most warehouse applications, an RF or Portable Data Terminal (PDT) is critical to accurately count and pull inventory. For additional information on which terminal to use, see the On-line vs. Off-line section under Radio Frequency Data Collection heading.