Sounds like the guy is trying to connect the plc to program. Even though HMI and DDE got mentioned because of the word "PC".
The last TWO post sound more relevant to what you are trying to do.
First can you tell us what kind of PLC? Look on the front for some numbers: 5/01, 5/02, 5/03, 5/04 or 5/05?
If you have a 5/03 or 5/04. You can use the radio shack special DB 9 cable. Start RS LINX, and click on Communications then Configure a New Driver.
Click on the pull down bar, and find
RS-232 DF1 Driver, normally the first one on the list.
Then click on ADD New.
The default name is ok. AB_DF1
Choose under DEVICE pull down box the choice: "SLC-CH0/Micro/PanelView"
Now here is the easy part. Make sure your Radio Shack cable mentioned above is connected to the DB9 connector on the front port of the PLC and you have the other end connected to the DB9 port of your computer.
Click on the button that says "Auto Configure" If you have the right cable and everything is connected right, you should get a "successful" in the box.
You should see your driver in the table below as running.
Next, close that driver box, then expand the driver on the left column. This will active it. Hopefully you'll see TWO icons in a second pop up.
One will be your computer, the other your PLC.
Now just minimize RS LINX and start your programming software RS Logix...if you need help from here, post back.
Chris Elston
Automation & Controls Engineer
Download Sample PLC Ladder Logic Code
at MrPLC.com