The need to upgrade existing PLC5 (or SLC500) systems to Logix5000 has become more pressing with Allen-Bradley’s assignment of the PLC5 family to its Silver Series. Silver Series is Allen-Bradley’s indication that while components are still available for purchase, they will soon be discontinued.
Considering the universal popularity of the PLC5, it can be assumed that the demand for replacement parts will very quickly outstrip the limited supply once new units are no longer available for sale.
Fortunately, in most applications, the upgrade path to Logix5000 is straightforward, provided some planning is done in advance. This 2 part blog series will outline some of the key decision points and recommendations for a successful upgrade program.
In most cases, the upgrade will have no net effect on the operation of the system, which is to say production rates, OEE, quality, and other metrics will be the same before and after the upgrade. This means that the primary criteria for selecting and prioritizing upgrade candidates are size, complexity, interfaces (discussed in more detail below), and available downtime windows.
It is most efficient if one (or more) upgrade teams consistently perform the work throughout a facility.
It is critical to understand beforehand exactly what needs to be considered in the upgrade. HMIs and other clients will need to be adjusted to communicate to the new PLC. Other PLCs connected to the upgrade subject will need to have Message instructions modified. Remote I/O or DH+ networks for drives, remote racks, and other devices need to be replicated, or upgraded to Ethernet.
Unlike a typical automation project, the design and testing phases for an upgrade can be significantly curtailed. When the Allen-Bradley software conversion utility is used, there is minimal development of new code, and the programmers doing the upgrade do not need to be expert in the process application.
This is a double edged sword, because while the engineering costs will be greatly reduced as compared to a typical project, it also means the automation team will not have the same level of familiarity with the system as if they had developed it from scratch. For this reason, it is very important to have plant personnel who are familiar with the operation of the upgraded system assisting with the startup. In part 2 we will discuss the software and interface needs as well as the training necessary for a successful upgrade.