Simatic Variables Monitoring/Recording


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I have a stand-alone Siemens S7 PLC on my platform for service air compressors. I have on my laptop Simatic S7/M7/C7 Version 5.1 SP4 Revision Level K5.1.4.0 talking to CPU 412-1. I do not have any HMI on it.

I had a trip 2 days ago and I want to monitor my Pressure Transmitters on the PLC.

How can I record a 'historical database' or 'trends' on the PLC? Is there a way of doing it?
Hi There.

I am afraid you cannot do it directly in the PLC as the memory is not designed to hold historical data, especially a long one.

In fact you can't do it on any controller as their memory is designed and used for fast read/write operation so they relatively expensive compared to disk memory.

You may consider of buying historian solution from many vendors available in the market. One of them is ITS-Industrial Turbine Services. They have a HMI solution to talk to S7 1200,300 and 400 and 400H controllers and record historical data (alarms, analog and digital signals)and trender.

You may contact them via info[at]

Good Luck

Randy Jakosalem

Dear Usman,

Your question is whether your S7 412 standalone PLC can do historical data on pressure readout. The answer is yes it can. BUT, in big letters it depends on the length of data and sampling frequency and the period you want it to gather data. Your PLC has a capability of storing data retentively in what is called as DATABLOCK. You can store 256 bytes in one datablock. You can use several datablocks to take turns when one is full. So when your simple question is "if it can", then the simple answer is yes it can. Though you need to have a programming skills to do it and the limitations of size.

by : Randy T. Jakosalem