PLC Programs

◼ All of our programs are extensively documented so that you know what the program does and can maintain the program yourself, if you want.

◼ In addition to developing new programs, we maintain programs that others have written. We troubleshoot hardware and program problems and make program modifications.

◼ For new projects we can provide PLC hardware bill of material and electrical drawings, as well as a functional description of the control to be provided by the PLC. With our partner contractors we can provide a turnkey service for the electrical control system.

◼ As with any program, writing a PLC program requires more than just a knowledge of the programming language. It also requires a system for program development. Without a system, programs tend to be written in a "stream of consciousness" manner and are unstable and difficult to understand and modify.

◼ Our system assures that our programs work as required - they do what they're supposed to do and don't do what they're not supposed to do. But, just as important, our system assures that the programs are easy to understand, easy to modify, and are well documented. This system consists of the following steps:

1. Development of a Functional Description.

This is a report that describes the devices connected to the PLC, the SCADA/HMI screens, the alarms, and a detailed description of the control provided by the PLC to include all interlocking conditions.

2. Development of flow charts.

Flow charts, which we term Grafcets, are developed based upon the Functional Description.

3. Development of PLC Program.

The PLC program is developed based upon the Grafcets. There is a one-to-one correlation between the program language and the Grafcets. So this becomes a data entry step.

4. Development of SCADA/HMI Screens.

The screens are developed based uppon the Functional Description.

5. Bench Testing.

The program is bench-tested to assure it meets the requirements of the Functional Description before installation at the plant.