How to use USB-TO-Serial Converter to connect SLC


Thread Starter


My new laptop don't have COM (1 or 2)Port instead of 3 USB port,so how to connect SLC serial port using RSLinx DF1 RS232 Driver?I have a USB-to-Serial Converter.
Just find out what com port your computer gives the serial converter and change to that port in Linx. My dell is the same way, and my converter works fine, it is just com 4 instead of com 1.
AllenBradley has a knowledgebase tech note on this on their web site at

You also cannot connect your USB converter cable directly to the PLC, you still need a crossover cable. You cannot connect to a PIC module with a USB converter. AB is supposedly coming out with a new PIC next year, but until that time, you will have to get a Serial Card for your laptop if you have to connect to SLC5/01 or 5/02 via the PIC. Connecting to SLC5/03 and above is no problem. I suggest you use the most recent version of RSLinx however, as some converters return a com port address higher than 4.

jasmin ouellet

Rockwell officially support 2 models of USB-Serial converter.these are Belkin F5U103 and Keyspan USA-19W

refer to knowledge base # A20896.

once you have one of these, they will probably be recognised as COM2 or COM3. simply use them as a regular COM1 port with an RS-232 DF1 driver.

************* Attention **************

USB to Serial DON'T work with a 1747-PIC... it's a matter of timing, and the new 1747-UIC is designed to correct that !




In my experience, I have gotten every USB-to-Serial converter I've seen
working with DF1, but Autoconfigure didn't work with some of them. This
means they worked with proper settings selected, but I had to determine
those settings by other means than Autoconfigure. Go to$$Search/?Op

and search for keyword USB to get a lot of recommendations that may apply
to your case.

Hope this helps!

Larry Lawver
Rexel / Central Florida