During meetings of introduction design topics such as: cycle rates, overall machine function, ergonomics, allowed number of rejects, project budget, safety, PLC platform, Machine Guarding, HMI are covered. The requirements of voltages and power will be stated by the targeted County and also existing power in the building or plant the system will be set up in. Various meetings may acquire position during the stage of mechanical design and in most cases in general specifications are completed by the customer. Electrical and Mechanical Engineers should work strongly through-out all stages of design.
Main items to be tackled during finding the Fact are as below:
Model and PLC Brand
Model and HMI Brand
Gear of Power Switch
Devices of Safety
Components and I/O Devices
Package of Controls used will be for a 4 Station Rivet Index Machine aimed for Europe and Asian and has the criteria as below:
4 seconds of Cycle Time
The Power is 380VAC 50Hz
24VDC Control Power
Light Curtain and Safety Switches of Guard Door
I/O points less than 100
Platforms of PLC:
Usually most manufacturers of PLCs have presented 3 PLCs platforms although that is varying and sometimes 4 to 5 platforms presented.
Below are the 3 PLCs Platforms presented in the past:
It is described as micro, shoe-box, and type of pico controllers. The sizes of PLCs are similar to a contact relay and can be increased on a DIN rail. Generally these PLCs have set I/O number points. Some have developed Outputs of Stepper Pulse and or a pair of Analog points. This kind of controller is aimed to small and simple machines and equipment of lab.
This PLC format is the most generally used in the industry nowadays and is pushing the Large PLCs Format out of the market. The reasons is due to the serial bus and networking capabilities of these new medium PLCs format. These PLCs Size formats are generally; 8 inches in height x 6 inches in depth x 20 inches in width. The I/O number can go into the thousands by operating; Expansion Racks, Serial Remote I/O, and High Density Cards.
These PLCs that put in this group are designed for larger and complex processes and machines. The systems of Automotive turn-key are a good pattern of aimed market for these PLCs. The sizes tend to be bigger than the format of medium, they are 14 inches in height x 7 inches in depth x 28 inches in width.