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Service

We also service PLC control systems and their associated HMI/SCADA's, not just systems we developed. This service includes system troubleshooting and system modifications.

Troubleshooting

When your system is shut down or not working properly, you need someone who not only will show up, but also knows what to do. Over the years we have serviced many different systems with just as many different problems. This gives us insight into how best to approach your problem and to get you quickly back on line.

A typical problem is a system that is shut down where the problem is initially thought to be with the PLC program. Often, after we investigate we find that the problem is with a particular failed input or output. Further investigation will indicate whether the field device failed or a PLC module failed.

There are times when the problem is with the PLC program. Some poorly developed programs can produce strange behavior following some unplanned for scenario. For these cases we identify the problem and develop the logic to prevent it from happening again.

Some problems are not so typical. This is illustrated by two examples. The first example involved a machine controlled by a PLC with an associated HMI. The HMI failed and we were asked to replace it. However, for this particular system the HMI would receive a security code from the PLC before it could interact with the PLC. This code was hard coded in the PLC, but would be entered as part of the HMI configuration. Unfortunately, no one knew the security code. We developed a temporary PC program that simulated the HMI and trapped the data from the PLC, allowing us to read the security code. The HMI was configured with this code and then could properly communicate with the PLC.

For the second example, a company purchased a PLC controlled system that was connected to a remote microprocessor based controller. After the system was installed, we were tasked with getting the system running. There was a PLC program, but it was not documented. Thus, we had to first investigate and document the program. Then we identified and fixed problems with the PLC hardware and field devices and established communication with the remote controller. After that, the system was started up and tested and was ready for production.

 

Modifications

There are times when we are called upon to add features to a PLC program or modify existing features. In order to do this properly we have to understand the current PLC program or at least the part that is to be modified. Over the years we have looked at so many different PLC programs and programming techniques that we are able to do this in a timely manner. Once we understand the current program, we can modify it with the new requirements.

Typically, new instrumentation is added to an existing system and wired to the PLC. We will configure the PLC to read the newly connected instrumentation and develop logic to incorporate it into the existing control algorithms. Other times, an existing control algorithm is to be modified or a new one added. We will make the appropriate program changes and test the new control.

These modifications are not limited to just the PLC. We often get requests to modify an existing HMI/SCADA screen or add a new screen. We have worked with all of the major HMI systems and also many of the minor systems. Once again, our experience with so many systems allows us to efficiently modify existing systems.