I’m an industry service engineer for food packaging machines instead of an automation specialist, but i can present you with few hints.
For many automation systems to operate, you should first use a clear and detailed mechanical plan effortlessly details finalized. When you do so, you need to specify the motions involved, e.g.: linear or rotary. This enables you to know the number and types of motors and actuators you may need(servo, ac single phase, ac 3 phase, pneumatic actuator).
For each motors you may 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.
They are your output devices, then you need your input devices being determined. This is level sensors, flow sensors, proximity switches and also other devices if required. The key reason why 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 is sold as reconfigurable rack chassis. Basically you will find the CPU which is master brain that’s supplemented with I/O device that could be slotted in like cards. Additional complex systems which needs servo motor will 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 figure out you IO devices list, then obtain the necessary software and hardware needed. You might need additional hardware required for for fancy touchscreen HMI, line automation and internet based diagnostic and asset monitoring functions. That’s what sort of guy with mechanical background can approach complex automation problems.
The solutions may differ based on different manufacturer offering especially if you use beckhoff based systems. A good way to start can be to work with existing machines so that you can learn the basics. Then go get yourself a few catalogs from reputable manufacturers to understand the market is offering. I usually suggest website visitors to go through Omron catalogues. There is also a totally free automation online course that may show you the newborn steps needed.
You should be able to design complete PLC systems: architecture design, hardware specfications and selection, logic narratives, logic programming, connection drawings. Everything. Perhaps you simply need extra training on the more knowledge about every bit of equipment, regarding how to program or properly connect them, but it is not rocket science, a good mechanical engineer should probably excel about this as any other engineer. The key element of control system design is to see the process you are going to control as well as the goals you need to achieve.