Previously, I’ve written about our history with code standardization and Rockwell’s support of standardization with Add-On Instructions and Plant PAx. But how do you go about developing and following a standard in the first place?
One of the most useful features of Rockwell’s RSLogix 5000 is the capability to create and leverage Add-On Instructions. A programmer can define one instruction that contains a specific set of instructions, thereby encapsulating a specific function or algorithm. Add-On instructions can be used to create new instructions for sets of commonly-used logic, providing a common interface and documentation. They are not the same as a high-level programming language. Note that Add-On-Instructions can be used across multiple projects and shared by other team members with each other. You add the instruction in to your program, connect up necessary references, and it runs!
When Optimation started standardizing code in 1998 for PLC Programming for the Allen Bradley PLC5, not too many others were practicing code standardization in the controls world. Now it’s considered a best practice, but is it always followed? What happens when you work with a systems integrator who doesn’t use standardized code?