The Siemens S-7 300 line of PLCs has about a million great features integrated into the programming environment. After I recently inherited a PLC project where some (many) of these were not implemented, I thought it might be a good idea to do a recap on some of the more useful functions Step7 has to offer us.

By far one of the most useful, and sadly underutilized, capabilities available to us from the Step7 environment is the “Report System Errors” utility. This utility, when activated, generates pre-built function blocks and adds them to your project. These FBs capture all diagnostic data and CPU messages, and spit it out in a human readable form perfectly compatible with the Siemens line of WinCC or WinCC Flex HMIs (though actually in fact, if you are particularly ambitious you can even use them on non-Siemens HMIs).

How much downtime has been wasted in your facility, while your maintenance team tracked down the cause of that annoying red “System Fault” light in the panel? Only to give up and pay for a programmer to come to your facility to plug in and see what the problem is? If this has happened to you, your programmer has not done his job. The RSE utility can give maintenance detailed diagnostics right on the HMI, sometimes more detailed than you might have thought possible. Instead of a blank “system fault” light and a line down for hours, imagine seeing the following on your HMI alarm log:

Name: IM151-3PN           Dosing Station 1 I/O Rack             SLOT 3                   Module: Port 2

Part Order number: 6ES7 151-3BA23-0AB0

Digital Input wire break

This is just one of thousands of possible custom error messages that get automatically added to your alarm list. You should be able to see right away why this should be in every S-7 300 project. This is the kind of thing that changes downtime from “hours” to “minutes”.

So why do I find PLC projects that are not using the RSE utility? Is it because system integrators don’t know about it, or because they don’t understand how it works? This blog solves the first problem. Stay tuned for the next blog, where I talk about how it works, and specifically how to use it on WinCC and WinCC Flex HMIs.