02 June 2010
Hardware running the control system at the plant was getting seriously out of date and FMA decided that simply updating the hardware was not an option. To address the problem, the team embarked upon a legacy upgrade programme, reworking, converting and modifying the existing SIEMENS S5 control system for the Contikeg 1000 kegging line to a state-of-the-art S7 system, implementing wireless technology at the plant for the very first time by incorporating ProfiNet wireless communications.For Plzensky Prazdroj, the advantages of switching over to SIEMENS S7 largely surrounded the avoidance of any maintenance and downtime issues and any resultant loss of productivity that might have been associated with an old legacy system using S5 PLCs.The kegging line at the brewery uses three automated carousels which pre-wash, wash and fill kegs 24 hours a day. The line handles an incredible thousand kegs an hour so it was imperative that the new control system could keep pace with this level of production. The carousels, which have been in operation for over 15 years, were each equipped with 12 S5-95U PLCs communicating to a S5 115U over a Sinec-L2 networkThe original solution used slip rings to bridge the Sinec-L2 to the carousels. While this solution worked adequately, limited network throughput meant that it was not suitable for high speed data transmissions as part of a new control system.FMA’s solution for bringing both the performance and reliability of the communication network on site up to benchmark standards involved installing ProfiNet and an Industrial Wireless Local Area Network (IWLAN) to provide seamless connection of the ProfiNet network, controllers and I/O modules.The company reworked, converted and modified the existing Siemens S5 software to S7 standards to work with new S7 hardware while HMIs throughout the site were upgraded to OPs to provide enhanced operator control. A total of 14 existing S5 115U and S5-95U PLCs were combined into one CPU416-3 PN/DP processor. All associated I/O was rewired to ProfiNet variants of both ET200M and ET200S remote I/O. On both the Pre-Washer and Washer carousels, the existing 12 S5-95U PLCs’ control was combined into a single ET200S CPU and the remaining stations converted to ProfiNet ET200S remote I/O devices. On the Filler carousel, meanwhile, the existing 12 S5-95U PLCs’ control was distributed across two ET200S CPUs and the remaining stations converted to ProfiNet ET200S remote I/O devices.FMA also commissioned Daconi, a specialist in wireless networks and technology, to collaborate with Siemens Industry Automation & Drive Technologies to conduct a wireless survey. Daconi determined the optimum wireless network architecture to give the best performance using Siemens simulation tools. A wireless survey was then performed using WiFi survey tools and imported plan drawings of the plant. The radio coverage of each access point was measured, and the optimum location for installation of the access points and the best antenna and antenna location for the wireless clients determined. The wireless solution was then tested in situ to verify performance. Brewery engineer Ondřej Sykora said: “Significant improvements to the efficiency of the site can be attributed to the installation. We have benefited from reduced downtime due to enhanced alarming functions which means we can find faults faster and rectify them sooner. We also now have quicker resumption of power in the event of a power outage, which has improved productivity. In addition, the reduction in the number of PLCs has meant we no longer rely so heavily on inter-PLC communications where problems were difficult to diagnose and remedy. Our service technicians have also found the PLC code easier to follow in S7 format and, again, this has kept downtime to a minimum and helped ensure the line runs as efficiently as possible.”
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