20.07.2004
Lately, the first point-of-sales device for weighing instruments with the possibility of downloading software for applications subject to legal control could be verified in accordance with the new European regulation (WELMEC 2.3, Annex III, 2002).
As to the operators of point-of-sales devices for weighing instruments, the software of the systems to be installed must meet the most different requirements. To be able to flexibly react to the desires of the customer, the possibility of software download is becoming more and more important for the manufacturers of such combinations. According WELMEC 2.3, Annex III (2002), software download means the possibility of exchanging software without destroying a verification seal. This summer (2003), the first PTB test certificate was issued for a download-capable point-of-sales system running on the hardware of a commercially available personal computer (PC), see Figure 1. This is possible due to the new development of an additional hardware, which allows the system to be operated only with a special software approved by PTB. This new hardware, which is accommodated in a small box, is directly integrated into the data path between weighing instrument and point-of-sales device and contains, among other things, a logbook (event logger) in which each loading process of new software into the PC is recorded. This is achieved by the fact that the software to be newly loaded must "log in" at the additional hardware during the installation process. Only if the additional hardware detects a correct check sum of the new software by a check sum comparison, is communication with the software established and the data path between weighing instrument and point-of-sales device released. Only then can the weighing instrument sent values to the point-of-sales device. Checking of the software of the point-of-sales device running on the PC is not, however, performed only once during loading and/or starting of the software, but also cyclically during operation. If the additional hardware detects a manipulation on the running software of the point-of-sales device, it immediately interrupts communication between the components. These protective functions and the existing event logger allow the manufacturer to react to desires of the customer, to further develop his software and to transfer it also into systems already in use, without destroying the verification seal. In the next examination of the point-of-sales device, the verification officer can reconstruct all loading processes performed with the aid of the event logger and check on the basis of the data recorded whether an approved software has been used at any time. Destroying of a verification seal will then be necessary only if the memory space of the event logger does no longer allow further loading processes to be stored. After destroying of the verification seal, a reset button is accessible which erases all data so far recorded. Further operation in transactions subject to legal control then require subsequent verification by a verification officer. In addition to the advantage of an increase in flexibility, software download implies a savings potential, as lesser subsequent verifications will be required.
Figure 1. Schematic representation of the first PC-based NAWI / POS-system with the possibility of download of software under legal control
Contact person:
Marcus Link, FB 1.1, AG 1.14, Email: Marcus.Link@ptb.de