Siemens Step7 CFC is a configuration tool that allows you to create and edit continuous function charts (CFCs) for programmable logic controllers (PLCs) in the SIMATIC S7 family. CFCs are graphical representations of control algorithms that consist of interconnected function blocks. CFCs can be used to implement complex control tasks that require parallel processing, branching, and looping.
In this article, we will show you how to use Siemens Step7 CFC to create a simple CFC for a PLC. You will need the following software and hardware:
Siemens Step7 CFC (you can purchase it from here)
Siemens SIMATIC Manager (included in Step7 Professional)
A SIMATIC S7 PLC (we will use S7-300 as an example)
A PC with an Ethernet connection to the PLC
The steps are as follows:
Open SIMATIC Manager and create a new project.
Add a new station and select your PLC model.
Add a new CFC chart under the station.
Open the CFC chart and drag and drop function blocks from the library onto the chart.
Connect the function blocks with wires according to your logic.
Assign inputs and outputs to the function blocks.
Compile and download the CFC chart to the PLC.
Monitor and test the CFC chart on the PLC.
For more details on how to use Siemens Step7 CFC, you can refer to the manual here.
Let's see an example of a CFC chart that controls a motor based on a temperature sensor. The CFC chart has the following function blocks:
A TON block that implements a timer on delay.
A GT block that compares two values and outputs true if the first value is greater than the second value.
A AND block that performs a logical AND operation on two inputs and outputs true if both inputs are true.
A Q block that represents an output to the motor.
The logic of the CFC chart is as follows:
If the temperature sensor value is greater than 50 degrees Celsius, the TON block starts counting.
If the TON block reaches 10 seconds, it outputs true.
If both the GT block and the TON block output true, the AND block outputs true.
If the AND block outputs true, the Q block turns on the motor.
The CFC chart looks like this:
To monitor and test the CFC chart on the PLC, you can use the online mode in Siemens Step7 CFC. In online mode, you can see the current values of the inputs and outputs, and force them to change manually. You can also see the status of the function blocks and wires, and troubleshoot any errors or warnings. To enter online mode, you need to connect your PC to the PLC via Ethernet, and select \"Go Online\" from the menu.