I’m an area service engineer for food packaging machines and not an automation specialist, however i can give you few hints.
For those automation systems to be effective, you should first have a very clear and detailed mechanical plan effortlessly details finalized. Once you accomplish that, you should specify the kind of motions involved, e.g.: linear or rotary. This allows you to understand the number and kinds of motors and actuators you will need(servo, ac single phase, ac 3 phase, pneumatic actuator).
For each and 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(a lot more like conveyors, liquid tank level control pumps or rollers).Servo motors need Servo drivers to regulate their precise movement.
These are generally your output devices, then you need your input devices to get put down. This could be level sensors, flow sensors, proximity switches as well as other devices when needed. The reason why i’m stating out this routine is usually to let you define the specifications necessary 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 master brain which is supplemented with I/O device that could be slotted in like cards. Additional complex systems which needs servo motor can have servo card in order 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 workout you IO devices list, then receive the necessary hardware and software needed. You may need additional hardware needed for for fancy touchscreen technology HMI, line automation and online diagnostic and asset monitoring functions. That’s how a guy with mechanical background can approach complex automation problems.
The solutions may vary depending on different manufacturer offering specifically if you use beckhoff based systems. The best way to start will be to work on existing machines so that you can educate yourself on the basics. Then go get yourself a few catalogs from reputable manufacturers to understand what the market provides. It’s my job to suggest people to go through Omron catalogues. They also have a no cost automation online course that can teach you the baby 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 just need extra training for the information each piece of equipment, on how to program or properly connect them, however it is not too difficult, a great mechanical engineer should probably excel for this as any other engineer. The most important aspect of control system design is to comprehend the process you are likely to control along with the goals you want to achieve.