How to communicate instructions from a host pc to a plc using serial connection

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I am currently beginning a project that involves communication between a host computer and a machine plc by means of a RS 232 cable.

Machine: High Cube II by Lauyans & Co. (It is a small parts storage and retrieval system used to store objects within a vertically large inventory unit shaped as a cube with multiple shelving units inside).

Capabilities: Controlled by a operator user interface, the machine picks and grabs storage shelves within the cube and lowers them down for the user to retrieve and place parts in the unit. The shelves have assigned numbers so that the user can type the desired shelf number into the operator's user interface. This interface is shaped like a small keyboard with a display screen showing instructions and whatever is input by the user. The interface is attached to the machine itself and wired to the logic controller.

My goal is to remove the manual step of typing in the location number into the operator interface and instead, command the storage system from a host computer and send the shelf number from there. With very little knowledge on serial communication and developing software, what steps should I take to create an application that will allow me to send the desired shelf input from my hosting computer and operate the machine?

There is a RS 232 input on the machines logic board for what is labeled as "host connection" so I plan on making the connection there. It seems like it would be easier to send keystrokes of the shelf number directly to the user interface but there in no available input option on the device. How do I open the ports for communication and develop a simple application with a text box to input a shelf and transmit it to the plc? Will it depend on the make of the plc? Thanks for any suggestions.

Posted 20-Jun-15 17:25pm

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[no name] 20-Jun-15 23:54pm

Are you doing this as a student or is this an actual business requirement?

Member 11780461 22-Jun-15 1:10am

Business project. The inventory is within a storage warehouse. The storage system's company provides software to purchase that will allow this host connection I speak of but I am conducting research to understand if I am capable of programming it myself to avoid expanding my department's budget

Sergey Alexandrovich Kryukov 21-Jun-15 0:04am

"Sending keystroke" is a bad thing. Do you have the documentation on the RS-232 part of the protocol?
—SA

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OriginalGriff · Answer 1 · 2015-06-20T19:34:00

The first thing to do is look at the kit itself and see what communications capabilities are built into it, and how you can use them - this probably means a look at the manufacturer's site and / or their technical support. There isn't necessarily a "common specification" for serial comms and unless you can program the machine itself directly (unlikely but possible) you will have to work within whatever framework they provide. Most manufactures provide documentation (but the quality can leave a lot to be desired!)

Once you know what data you have to send / receive and how to do it the PC side should be relatively simple, if you are familiar with serial comms already. This should help a lot: Serial Comms in C# for Beginners[^] - Glen is an electronics engineer who also does coding, and it covers it all pretty well with examples.