It is an introduction to SIEMENS S7-200 PLC. It will help in Industrial Automation.
A Programmable Logic Controller (PLC) is a small computer that observes the status of input devices and controls the status of output devices based on the program in it. Siemens is one of the leading conglomerates in PLC manufacturing. They have three types of PLC.
In this article, I will discuss about the most common and famous Micro PLC of Siemens, known as S7-200 Series PLC.
The basic element of a PLC consists of Input Modules, Output Modules & CPU (Central Processing Unit). Generally, Input Modules are two types, Digital Input Modules & Analog Input Modules. As well as Output Modules are also two types, Digital Output Modules & Analog Output Modules. In addition, the CPU can be classified in different types based on their built in I/O modules, program memory, power supply etc.
There are many CPU models designed for S7-200.
CPU-221, CPU-222, CPU-224, CPU-224XP, CPU-224XPsi, CPU-226 are the most common and used CPUs. CPU-221 has six inputs and four outputs. It is not expandable with Expansion Module. CPU-222 has eight inputs and six outputs. Maximum 2 Expansion Module can be added with it. This CPU can handle maximum 94 I/O. CPU-224 has 14 inputs and 10 outputs. Maximum 7 Expansion Module can be added with it. This CPU can handle maximum 224 I/O. These CPU has built in RS 485 Serial Networking Port for communication and Memory card for data logging, recipe management, saving of STEP7/MicroWIN Project. Memory card is available with 64 KB or 256 KB. CPU-224XP has 14 inputs, 10 outputs, 2 Analog inputs and 1 Analog Outputs. Maximum 7 Expansion Module can be added with it. This CPU can handle maximum 224 I/O. It has also one more built in RS 485 Serial Networking Port for communication. CPU-224 & CPU-224XPsi are almost same. The basic difference between them is CPU-224XPsi has current sinking digital outputs. CPU-226 has 24 inputs and 16 outputs. Maximum 7 Expansion Module can be added with it. This CPU can handle maximum 256 I/O. It has also one more built in RS 485 Serial Networking Port for communication.
In short, above mentioned all CPUs have integrated digital inputs/outputs. However, their quantity varies from model to model. Program memory of CPU-221 & CPU-222 is 4 KB. Whereas, program memory of CPU-224, CPU-224XP, CPU-224XPsi & CPU-226 is 8/12 KB, 12/16 KB, 12/16 KB & 16/24 KB respectively. High Speed Counter (HSC) is also a vital part of CPU that is used to count high frequency pulse coming from encoder or any other devices like this. CPU-221 has 4X30 KHz HSC, CPU-222 has 4X30 KHz HSC, CPU-224 has 6X30 KHz HSC, CPU-224XP, CPU-224XPsi has 4X30 KHz & 2X200KHz HSC and CPU-226 has 6X30 KHz HSC.
The height & depth of all CPUs are 80 mm & 62 mm respectively. On the other hand, the width of CPUs is different for different model. Width of CPU-221 & CPU-222 is 90 mm. Width of CPU-224 is 120.5 mm. Width of CPU-224XP & CPU-224XPsi is 140 mm. Moreover, width of CPU-226 is 196 mm.
Next I will discuss about the I/O Modules and furthermore about programming, troubleshooting of S7-200 PLC.
Thanks for reading this article. If you have any query, feel free to contact with me. Thanks to all.
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