Any experts on touchscreen programming here?

I need help.

I have a process controller for a technology I'm developing (in the wine space), the prototype runs on an Atmel uc with a keypad (numeric) entry and an LCD display.

Everything works but I'd like to port the control over to an industrial PLC, partly for robustness and partly because I know these PLCs and can program them myself and thus tweak parameters easily. I also want to move to touchscreen input and display: I can also program the HMI that normally lives with the PLC but I hate it, it's clunky and it complicates the power supply design.

I would love to replace it with something smaller and brighter and easier to power like the displays from 4D systems here in Aus. The people who run 4D systems tell me that their controllers can be configured to talk modbus so it should be easy to do but the info they send me assumes a level of familiarity with programming touchscreens which I just don't have.

Basically I need to talk to someone who knows I'm not an idiot and can explain what it is that I'm missing. I'm happy to pay you for your expertise.