Introduction to Industrial Automation

Figure 10.5  Machine for production of tzatziki salad (a), digital balance output (b), I/O device 

connections in PLC (c).

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Industrial Applications 

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  5. Two photoelectric switches (with SPDT outputs) detect the presence of the plastic con-

tainer below the outlet of the dosing pump. The two photoelectric switches are necessary 

due to the small gap between the two successive containers. When there is no plastic 

container below the pump outlet, the pump stops and operates only the conveyor until 

it brings the container below the pump outlet. Then the dosing pump starts to operate 

again.

  6. The applied recipe requires 80 Kg yogurt, 20 Kg minced cucumber, and 5 Kg garlic 

pulp.

  7. The filled containers must be counted. The applied recipe corresponds to approximately 

300 filled containers. If for any reason there are fewer than 300 filled containers, then the 

indication lamp H turns on.

  8. After the emptying of the tank vessel, all parts of the system stop or reset and the machine 

is ready for the next START signal.

It is recommended to write the required program in Boolean or IL language and use modular 

programming.