Terminal assignment of the S7-200 (CPU 221)
Cyclic program execution in the S7-200
All SIMATIC controllers operate cyclically. The cycle begins with reading the input states and transferring them to the image memory of the MIE inputs (input acquisition phase). This process image is the source of the program for its execution. During processing, the program stores the results of the operations in the image memory of the MIS outputs. At the end of the program, the states contained in the MIS are transferred to the physical outputs (output emission phase), and the cycle resumes at the beginning.
Interface configuration for PC / PG-API link
- Click on the communication icon in the navigation bar.
- Check the communication parameters.
- Double-click on the update communication field. The software should then identify and register the connected CPU on its own.
- If the CPU is not identified or if a message appears indicating that communication is not possible, double-click on the PPI cable field.
- In the PG / PC interface, select the PC / PPI cable and click on Properties.
- In the PPI window, set the CPU address to 2 and the baud rate to 9.6 kbits / s.
- In the Local Connection window, select the interface to which the PC / PPI cable is connected.
- In each window, confirm your choice with OK. 7.
- In the Communication links window, double-click again on the communication update field.
- The CPU is then identified and registered automatically. This operation may take a few seconds.
- Then close the Communication links window.
Combinatorial bit operations use two digits: 1 and 0. These two digits are the basis of the binary numbering system and are called binary digits or bits. For contacts and coils, 1 means activated or energized and 0 means deactivated or de-energized. Bitwise combine operations evaluate signal states 1 and 0 and combine them according to Boolean logic. The result of these combinations is equal to 1 or 0. This is the logical result (RLG).
There are combinatorial bit operations to perform the following functions:
Networks are used to structure a program. We enter each circuit in a network.
The other modes of representation are the instruction list (LIST language) and the logic diagram (LOG language). In the View menu you can switch between the languages LAD, STL and FBD.