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Reliance SCADA and a direct driver for Siemens SIMATIC S7 PLCs

November 2, 2015 | Bretislav Valek

The following article was taken from a review by Mr. Jaroslav Blazek who tested the connection of a Siemens SIMATIC S7 PLC to the Reliance system. The original Czech version of his article can be found at

When using any visualization application, a direct, native driver for the most widespread PLC – SIMATIC S7 – is an undeniable advantage. You don't need any OPC server, just connect the PLC to Ethernet. The Reliance 4.6.2 SCADA system is endowed with such a driver, so let's check out how it works.

Watch the video at the bottom of this article.

Go to the Device Manager and select the Siemens device (PLC) type. The following models are available: S7-200, 300, 400, 1200, 1500, and LOGO!

Device Manager, Reliance SCADA

Device Manager

On the device's Basic page, you only need to set the PLC model to S7-300, S7-400, S7-1200. If the S7-1200 model is used, set the Slot property to 1 (for the other models as appropriate). If a necessary communication processor for S7-300 is used, the slot must be set to the position of the PLC (not processor), i.e., to the most usual position 2.

Note: The TSAP properties are used for communication with Siemens LOGO!

Device properties

Device properties

There's no need to change the communication channel settings. The PLC's IP address can be specified either through the Project Structure Manager or – as in this project – via the Device Manager.

Project Structure Manager, Reliance SCADA

Project Structure Manager

Now you just need to define some tags for the PLC. For each tag folder, the update interval can be configured. The Reliance system also allows importing tags defined directly in the TIA Portal environment. Simply read the tags exported from TIA in the XLSX format. Importing objects from TIA Portal is very quick. After that, put the tags into their respective folders.

Import of tags, Reliance SCADA

Import of tags

Our tags' update interval is set to 500 ms. All the other common tag properties can be configured using drop-down menus.

Tag properties, Reliance SCADA

Tag properties

This window is designed for testing purposes and it's quite clear what the tags and formulas are intended for.

Note: We tried to import some graphics through the Picture Manager – just a logo, pictures of the PLCs, and signals. For the sake of completeness, it should be added that communication was tested with a SIMATIC S7-1200 PLC.

Visualization window, Reliance SCADA

Visualization window

If you want to view communication with the PLC, add a Container component to the visualization window and select the communication channel. You can see a little bit what's going on in communication and how long it takes.

Container, Reliance SCADA


After project startup, the application establishes a connection with the PLC and tags are read. At the bottom of the container, you can see the number of read, error, and timed-out packets.

Communication in detail

Communication in detail

If you rip the cable from the PC or PLC, the connected objects are framed in yellow and the numbers, of course, freeze.

Visualization in Reliance 4 Control Server

Visualization in Reliance 4 Control Server

Besides, the Current Alarms/Events window showing the problem is displayed. When you replug the cable, the connection is reestablished and everything starts again (see the video below).

Current alarms/events, Reliance SCADA

Current alarms/events

Watch the video that shows the settings, online mode, and communication between Reliance SCADA and the SIMATIC PLC. (Note: Only in Czech)

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