In early 2009 Tait Controls undertook the upgrade of Canpac's can line production monitoring system, after an extensive investigation into the existing networks and PLC code. In a two month period the four can filling lines were migrated from the old system to the new system, utilising short breaks in production schedules.
Commissioning began with two less used lines, which mean that debugging was carried out with minor impact on production. Conversion of the second two lines was without incident, which was important because production from these lines was highly monitored for international customers.
The upgrade was centered around the replacement of a PLC5 SoftLogix PC with ControlLogix, and the replacement of custom database interfacing software with RSSQL. Two DeviceNet networks with twenty three devices were involved, four DH+ messaging connections to PLC5 processors, Ethernet connections to four message displays and two other ControlLogix processors, six legacy Panelview applications, and four RSView32 applications (which were changed from DH+ connections to Ethernet). In the new PLC software device interfacing was separated from system functionality, facilitating future component upgrades.
The success of the project and short commissioning times were largely due to the detailed investigation and planning carried out before hand, as part of a separate project. This approach worked well for both Tait Controls and the customer, because there was no clear functional description, and because it was initially very hard to determine the scope of work.