Hi there and thanks for the response,
After looking through the specs, it looks like its PLC dependant. So I suppose the Arduino would have to emulate a PLC. I have in no right mind, any idea how to do that.
I've managed to make my own cables as I have the pinout of the adapters on the back, they almost all go to a db9 serial adapter, except one, which is a 15 pin adapter.
The HMI also has an Ethernet port enabled, but I doubt I have the module for that...but maybe.
So yes, I guess I'm trying to emulate a PLC.
And nice work by the way
The answer to your question is that you need two things: 1. An RS-232 to TTL serial converter; 2. Software.
1. a few dollars on ebay
2. read HMI manual. It tells you baud rate and how to talk with it, mostly how to listen to it if there is a custom mode.
An HMI is usually connected to a PLC unit to be used as the operator's panel. It will periodically poll or receives values on the PLC registers (most know how to talk to certain brand PLCs) and displays them on the LCD. You may change some of these values on the panel. If your panel has a custom mode where it only sends out values when you press a key, then you can use it on an arduino. Otherwise you have to emulate a PLC. Is that what you want?
I spent some fair amount of time trying to find some HMI to work with Arduino but I only bought one and didn't get it to work. So I designed these http://www.inmojo.com/store/liudr-arduino-and-physics-gadgets/item/serial-16x2-lcd-keypad-panel---phi-panel/http://www.inmojo.com/store/liudr-arduino-and-physics-gadgets/item/serial-20x4-lcd-keypad-panel---phi-panel/
10 number keys 4 directions and enter/escape