I’m a field service engineer for food packaging machines and not an automation specialist, but i can present you with few hints.
For many automation systems to function, you have to first have a very clear and detailed mechanical plan effortlessly details finalized. When you achieve this, you have to specify the type of motions involved, e.g.: linear or rotary. This allows you to have in mind the number and types of motors and actuators you will need(servo, ac single phase, ac 3 phase, pneumatic actuator).
Per motors you may want relay contactors (for single speed discrete/on-off type motors like blower fans and liquid pumps), VFD for speed controllable ac 3-phase motors(much more conveyors, liquid tank level control pumps or rollers).Servo motors need Servo drivers to manipulate their precise movement.
They are your output devices, you’ll need your input devices being set out. This is level sensors, flow sensors, proximity switches and other devices as needed. The reason i’m stating out this routine would be to let you define the specifications required for your control system hardware requirements. All PLC manufacturers layout their product line-up depending on system complexity.
Most PLC hardware is sold as reconfigurable rack chassis. Basically you will find the CPU the master brain that is supplemented with I/O device that may be slotted in like cards. Additional complex systems which needs servo motor will have servo card to connect 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 figure out you IO devices list, then get the necessary hardware and software needed. You may want additional hardware needed for for fancy touchscreen HMI, line automation and internet-based diagnostic and asset monitoring functions. That’s how a guy with mechanical background can approach complex automation problems.
The solutions could differ based on different manufacturer offering especially if you use beckhoff based systems. A sensible way to start will be to develop existing machines so you study the basics. Go have a few catalogs from reputable manufacturers to understand what the market is offering. I suggest people to go through Omron catalogues. They also have a free of charge automation online course which will educate you on the infant steps needed.
You need to be capable to design complete PLC systems: architecture design, hardware specfications and selection, logic narratives, logic programming, connection drawings. Everything. Perhaps you simply need some additional training around the information each piece of apparatus, concerning how to program or properly connect them, but it’s not brain surgery, a fantastic mechanical engineer should probably excel on this because other engineer. The most crucial aspect of control system design is always to understand the process you will control and the goals you want to achieve.