Question Raised:
Siemens 1200 PLCs are available in multiple models; how should one select the appropriate one? Different part numbers within the same series of PLCs may vary in terms of dimensions, built-in working memory size, built-in load memory size, built-in IO points, number of expandable IO modules supported by the base unit, number of network ports, size of the retention memory, number of communication modules supported by the base unit, number of signal boards, processing speed, communication capabilities, and the number of motion control axes. The overwhelming amount of information and lack of experience can make it difficult for some users to select the correct PLC.
Solution:
The official Siemens PLC selection guide is our primary reference for selecting PLCs. The table below lists the main parameters of the PLC. Comparing different parameters makes the selection process much more manageable. We need to understand the meaning of these parameters and their relationship to the PLC hardware.
Experience Sharing
l When selecting a Siemens PLC, looking at every parameter is unnecessary. We can choose based on the main parameters. For example, you need a 1200 series PLC with two communication network ports and support for differential pulse input and output on the base unit. In that case, you can determine from the selection guide manual that the CPU 1217C is what we need.
l Suppose your starting point for selection is sufficient and cost-effective. For instance, if you only need four inputs, two outputs, one network port, and no expandable IO modules, then the CPU 1211C is recommended.
l When selecting a PLC, it is advisable to have some margin. For example, the number of input and output points should not be just correct; it is appropriate to have a little more to consider future changes in functionality or damage to IO points.
l It is important to note that after determining the PLC model through the selection guide manual, the part number must be recorded, as it will be used when purchasing the PLC.
For previous part, please refer to the link: Critical Considerations for PLC Selection
