A simple SCADA system with S7-1200 PLC for

processing machine monitoring and logging, using TIA PORTAL and user defined webpage

Posted by george vakfaris on October 13, 2018

This article presents the User defined webpage, that is part of the webserver ot S7-1200/1500 PLC series of SIEMENS. Instead of using the OPC Server to download online data from PLC to PC, you can achieve it directly as shown here. You can therefore avoid using a third party software to process the OPC Server data received.

The application was developed to monitor real-time temperatures, steam pressure, conveyor belt speed and processing cycle time of a Vegetables Blancher. At the same time, a trend chart provides real time graph information and the PLC is logging all kind of data that can be either downloaded manually or automatically every 24-hours interval to the PC.

A great article about how to develop the user defined webpage easily and step-by-step can be found at DMC software development website.

SCADA main display with the gauges and trend graph.

The app is installed in a Vegetables Blancher to monitor and log processing data. The machine is used to blanch (cook) vegetables prior to IQF freezing.

*Blanching refers to the process of immersing vegetables into boiling water or steam for a timed period and then rapidly cooling in cold water to prevent further cooking. Blanching inactivates vegetable enzymes, allowing blanched, frozen vegetables to have better quality over time.

          ZACMI vegetables blancher.

The display monitors in Real Time the following values:

  • -Preheating, blanching (cooking) and cooling temperature
  • -Infeed steam pressure
  • -Conveyor belt speed and cycle time (product infeed/outfeed)
  • -Logging status and Log file (.csv) download button
  • -Real time trend graph with blanching temperatures

The gauges used are from JustGage while the trend chart is implemented using Smoothie Charts javascript library.

Old monitoring and logging system (local).

The application is also mobile ready (responsive) and can be visited by any internet connected device through a browser. The User Defined Webpage provides the advantage of making the application available without the need to install any special software, just use the web browser you prefer and make it accessible from everywhere through any device (pc, tablet, mobile).

The app shown on a smartphone browser.

Operation
The system monitors in real time process data like temperatures, steam pressure, belt velocity. All data are shown in the User Defined Webpage that is running on the PLC web server. The PLC download to the PC automatic a data file every 24-hours interval. This file can be further processed with a software like MSExcel and includes all the measures every 2seconds. Alternatively, the user can manually download the last 24-hours data file by pressing the Download Button. No Remote Access and control priviliges are granted to the specific app. It can be done by adding the necessary buttons, toggles etc but should be taken into consideration all safety aspects of a remote control in order to avoid injuries or accidents.

The data being processed with Microsoft Excel software.

An Excel sample file excel can be found here

While a working example of the SCADA display is available online at this DEMO link.

Hardware used and software development

For this application we used the SIEMENS CPU 1211 DC/DC/Rly with the SM1231 RTD signal module (ordering code 6ES7231-5PD32-0XB0), which offers 4XAI/PT100. Further to this, an IP should be assigned to the CPU and connect it to a modem/switch. Monitoring is then displayed on any web browser and is therefore cross-platfom.

PLC devices configuration. Reading Analog Inputs. To display PT100 Temperature value, you must divide by ten. The analog inputs like pressure, velocity etc are pocessed with NORMALIZE_X and SCALE_X function blocks.

Logging procedures are implemented with TIA PORTAL DataLog instructions such as DataLogCreate, DataLogOpen, DataLogWrite, DataLogClose. User Defined Webpage implementation is clearly described in the DMC article, as mentioned above. No need of OPC Server is required to process data on PC.

HTML webpage is made using Bootstrap 4 front-end, AJAX and pure Javascript. Also applied all the above javascript libraries for the gauges and trendline graph.

Text and images by george vakfaris.