DHL Express – PolandBCS Polska implemented on-line identification system for pallets on
The principles of the system
System based on Symbol terminal and wireless communication (online transmission of the data)
- identification of the pallets: parcel code, postcode, weight,
- complete two-way communication and real-time work,
- complying with GUM norms (scales on fork-lift trucks)
- use of PDT3146 manual terminals DHL Express works with,
- return of the ROI investment in less than 6 months' time.
Solutions offered by the design team of BCS Polska and DHL Express involve the combination of new technologies and were a huge challenge as the following aim was established by DHL Express: real-time transfer of all identifying parameters of a pallet (parcel code, postcode – written down in bar code form, and the weight of a pallet) to the database and sending the return information to the operator to direct it at the appropriate loading terminal. The system de facto should:
- register the fact of "passage" of a pallet through the sorting office,
- register the pallet's parameters (postcode, parcel code, weight),
- communicate online with Oracle Database Server,
- control the process of further loading of a pallet (direct it at the appropriate terminal),
- respond to all unusual situations (unstable weight, uncalibrated scales, absence of radio network, absence of the manual terminal operator, etc.)
- work in compliance with regulations governing industrial automatic machinery range (automatic work, manual work, emergency work).
Variety of interfaces
The fundamental issue was suitable connection and synchronization of all communication links:
- electronic scales on forks with RS-232 interface (batch work in question mode)
- VRC8946 truck terminals with Spectrum24 wireless communication (connection to a server), application in PocketPC environment, local database (safe devices in case of fading), RS-232 connector (interacting with scales), bar code scanner (work in manual mode where truck operator reads parcel code and postal code himself)
- PDT3146 manual terminals with Spectrum24 wireless communication, application in client-server technology (truck identification, bar code reading),
- WaveLink server (client-server technology) to operate PDT3146 terminals and interact with TCP/IP server,
- TCP/IP server to operate applications in VRC8946 terminals and to interact with Oracle through DLL library,
- DLL library to exchange data between the scale system and Oracle (transmission of data concerning the pallet, return the information concerning so-called "direction").
Variety of devices and applications
The already functioning systems and devices were integrated into the new system. Certainly, the extension of that base to new devices and applications was necessary.
- Spectrum wireless LAN by Symbol Technologies,
- VRC8946 wireless truck terminal with keyboard,
- PDT3146 manual wireless terminal,
- P302FZY manual bar code reader,
- Ravas scale for the fork-lift truck with transmission converter (connector RS-232).
- software for VRC terminal (PocketPC platform),
- software for PDT3146 terminal (WaveLink platform),
- communication software – communication server,
- software for superior system (DLL library relating to "business logic" of Oracle system.
Process implementation by stages
The following model of the measurement of pallet parameters was planned:
- the division into basic stages (procedures) – sequences performing identification,
- back up procedures when the automatic procedure is not possible,
- measurement to take place in the designated area; the fork-lift truck drives up to the operator where all procedures will be done automatically,
- data is sent to the override system via two channels:
- by VRC8946 wireless truck terminal (weight value from the scale converter, pallet's code when reading by PDT3146 manual terminal is not available),
- by PDT3146 manual terminal (start of the procedure, truck's ID, parcel code, postcode, end of procedure)
Three operation modes are designed into the project:
Within the basic operation model (with two terminals: VRC + PDT) the truck driver takes the pallet and drives it into the measurement area where another operator with a PDT manual terminal is waiting for him. The truck driver approaches the operator who scans the bar codes on the parcel as well as the code appearing on the fork-lift truck (truck's identification). When the truck ID is scanned, the pallet is automatically weighed on the PDT terminal's command through the direct connection of TCP/IP to the VRC truck terminal (electronic scales installed on the forks are connected to VRC). The use of the PocketPC platform allows us to create a TCP/IP server that handles commands relating to weight identification. If the scales are not stable, the truck driver receives a clear message: 'scales unstable'. When the scales are stabilized, the identification data is completed (weight, scans of the bar codes - parcel code and postcode as well as the information about the weighing time) and this is sent to the central system. On the basis of the postcode scan, the information about the parcel direction is taken from the central system. The truck driver and the warehouse manager receive a clear message about the data completion as well as about the target terminal. After this operation, the truck driver can see the following data displayed:
- abbreviation of the next HUB that the parcel is going to pass through in capital letters,
- the target terminal in smaller letters, i.e.: WA-LU.
The cancellation of the direction takes place while the pallet is being taken down from the forks (it prevents the truck driver from confusing the direction during the drive time).
When there is only a VRC terminal working (in the measurement area there is no warehouse manager holding a PDT terminal), the truck driver has to get off the truck and scan the postcode and pallet code using the scanner connected to the VRC terminal. After this operation, the command for the pallets' weight is automatically sent. All data is shown on the terminal's display and the data set is saved onto the system.
Where there is a lack of a radio network, the VRC terminal continues to function fully. It is capable of collecting data and buffering it onto the local file. When the wireless transmission is resumed, the collected data is automatically sent by the application on the VRC terminal. When the situation requires the manual transmission of files with the data, the terminal should be connected to a PC and the files with buffered data copied over. However, this would occur only in an emergency and there is little likelihood of it happening.
The system uses the login procedure to verify users working with the application. This is done by entering a username and a password. Where two terminals are in use, DHL Express identifies which terminal is saving data, by way of an ID. Display windows appearing on the VRC terminals.
The PocketPC platform allows the creation of a legible and full-screen user's window. In addition, by working in a multi-functional environment on a VRC terminal, this application can control reading the weight on the scales whilst at the same time receiving commands from PDT terminals relating to stating the actual weight of the package. Windows appearing on PDT terminal.
Algorithm of the system's operation – communication
The truck driver takes the pallet with the goods and proceeds to the area where the parcels are to be scanned i.e. the measurement area. After driving into the measurement area, the sorting office operator fulfills the procedure of the identification of the pallet as well as the truck. The procedure is as follows: the manual terminal reads the truck code (the label with a code stuck to the truck), the pallet's code, and the postcode – this data is recorded by manual wireless terminal - PDT3146 and sent to the WaveLink server by the application. During the truck's identification by a manual terminal operator, the weight of the pallet on the raised forks is automatically taken. The weight data are sent to the VRC truck terminal through the RS-232 connector and from there they are transferred to the TCP/IP server. While all data is being gathered and compared, the server sends them to the Oracle server. The Oracle server saves the data onto its database and returns the data concerning the direction of a parcel together with confirmation to the truck driver. After the above process, the operator receives displayed information about the direction of a parcel which prevents possible mistakes during the sorting of parcels on a pallet. The main task of the TCP/IT server is to integrate the data coming from the manual terminal (truck code, pallet code, postcode) and from the truck driver terminal (truck code - the fixed code, the same as the one appearing on the truck identifier, the weight of a parcel). At the end of the procedure of weight measurement, the confirmation of the proper performance of the procedure is displayed on the truck terminal together with the direction in which a particular pallet is to be sent. Identifying the truck when the information about the pallets is being gathered - is key to the system. The system is designed to be very flexible - the manual PDT terminal isn't tied to the VRC terminal. Every time the truck approaches the operator with a manual terminal, the truck is being identified (at this moment the system knows which truck terminal should be asked for weight value) then, the codes and the weight of the pallet are read simultaneously. The data is sent to Oracle and onto the terminal screens together with information on the direction in which the parcel should be sent.
The system allows that each truck terminal works automatically with the manual terminal as well as without them (codes reading through the bar code readers).
The main work mode of the system, as the most efficient solution, is the interaction of PDT terminals with VRC truck computers. During the operation, the WaveLink server enables direct communication between PDT terminals and the appropriate VRC computer. The communication process uses TCP/IP protocol.
When it is necessary to work without PDT terminals (without the warehouse manager) the independent information flow path is used. The application on VRC omits the WaveLink server and using the working system it connects to the DLL library, through which it enters the data into the system as well as takes up return information. This solution, separating paths of information flow, guarantees better reliability than using the second work mode, where the WaveLink server communicates with the DLL library. If, whilst in that mode, there is a system failure, the user will be informed about it and data will be automatically buffered onto the VRC computer's memory. When communication is restored, the data is sent to the central system.
Capabilities of the system
The system was introduced as the WaveLink platform has already been used in DHL Express. This technology enables the single-thread operation of the application so that simple terminals can use it.
PocketPC platform is a multithread platform that enables the application of asynchronous data exchange. This is an innovative platform used for the most demanding applications (this platform serves communication with scales as well as with TCP/IP server). Additionally, the PocketPC platform is also able to function in cases of a malfunctioning wireless network. The manual scanner that is available on the truck can be used then and the data is buffered into the terminal and sent after the wireless network is restored, or sent manually after the terminal is connected to the PC.
Further development of the system
Further phases in developing the system of identifying pallets are planned as follows:
- Automatic identification of the truck, automatic code reading, automatic weight reading; position for the procedures' execution, equipped with PLC driver (controlling, signaling, converting the data from sensors, data transmission), stationary bar code reader, RFID readers, signaling equipment carrying out the measurement, presence sensors. The trucks will be equipped with RFID identifiers.
- Automatic execution of all measurements – the measuring instruments will be added to the position and the PLC will be programmed to calculate the volume.
The above-mentioned system presents the combination of many innovative technologies (taking the weight directly at the fork-lift trucks, data transmission through the wireless channel, manual and truck wireless terminals, client-server technology, communication with the Oracle server through DLL interface).
On the other hand, it is a solution which is one of the first such solutions in Europe, and one which shows the potential of our engineers and programmers. The most important technical standard is to shorten the reading and the weight recording from approximately 30 seconds to 2, not mentioning additional important elements (complete communication, online recording, control of the shipment's direction, etc.).
We would like to emphasize that the design solution met its expectations and resulted in the improvement of DHL Express' work standards as well as bringing expected economic profits. Thanks to this solution, DHL Express consolidated its TSL market position. Conducting and coordinating the project was a very important element. Workers coming from different companies fulfilled this task: DHL Express (customer, communication with Oracle), BCS Polska (prime contractor, equipment, and communication), Income (software and communication systems), Progress Scales (scales on forks).