I’m an area service engineer for food packaging machines and never an automation specialist, however i can give you few hints.
For all those automation systems to be effective, you should first use a clear and detailed mechanical plan wonderful details finalized. Whenever you do this, you must specify the motions involved, e.g.: linear or rotary. This lets you be aware of number and kinds of motors and actuators you will need(servo, ac single phase, ac 3 phase, pneumatic actuator).
For every motors you might need relay contactors (for single speed discrete/on-off type motors like blower fans and liquid pumps), VFD for speed controllable ac 3-phase motors(more like conveyors, liquid tank level control pumps or rollers).Servo motors need Servo drivers to regulate their precise movement.
These are your output devices, you will need your input devices to be put down. This can be level sensors, flow sensors, proximity switches as well as other devices if required. The reason i’m stating out this routine is always to let you define the specifications essential for your control system hardware requirements. All PLC manufacturers layout their product line-up depending on system complexity.
Most PLC hardware comes as reconfigurable rack chassis. Basically there is a CPU which is the master brain which can be supplemented with I/O device which can be slotted in like cards. Additional complex systems which needs servo motor can have servo card for connecting with servo driver, communication bus cards like CAN-BUS, PROFIBUS and DEVICENET and sensor cards for special sensors like RTD temperature sensors and level sensors.
So exercise you IO devices list, then obtain the necessary software and hardware needed. You may need additional hardware required for for fancy touchscreen display HMI, line automation an internet-based diagnostic and asset monitoring functions. That’s the way a guy with mechanical background can approach complex automation problems.
The solutions could differ determined by different manufacturer offering specifically if you use beckhoff based systems. The best way to start can be to work with existing machines so that you will learn the basics. Then go get yourself a few catalogs from reputable manufacturers to understand what the market industry can give. I always suggest people to go through Omron catalogues. They also have a free of charge automation web based course that may coach you on the baby steps needed.
You should be capable to design complete PLC systems: architecture design, hardware specfications and selection, logic narratives, logic programming, connection drawings. Everything. Perhaps you simply need extra training about the more knowledge about each bit of it technology, on the way to program or properly connect them, but it is not too difficult, an excellent mechanical engineer should probably excel with this because other engineer. The most crucial facet of control system design is to understand the process you are going to control as well as the goals you want to achieve.