Connecting notebook to PLC


Thread Starter


I have a notebook which do not have com port (db9) but ps/2. How can I connect to PLC?
All notebook/laptop computers have a PCMCIA port and most notebooks since 1999 have at least one USB port.

There are numerous USB to serial adapters on the market, some seem to work, others don't. I have a no-name USB-to-serial adapter that works fine, but I have spent several hours trying a couple others that didn't work.

PCMCIA to serial adapters made by Socket, ( seem to work almost all the time. These cost more than USB-serial adapters, but others I have talked to seem to agree that the PCMCIA-serial adpaters are more rugged.



Robert Scott

Get a USB-to-COM port adapter. Now your PC has a COM port.

Robert Scott
Real-Time Specialties
Embedded Systems Consulting
I use a USB to serial port converter (Belkin). Somewhat inexpensive and works well. Not sure about PS/2, I doubt that would work, but you probably have USB.

You can get an USB/RS232 converter.
There are two types:

- without external power supply (not recommended)
- with external supply (a bit more expensive)

Hope useful.

Aquilino Rodriguez

Brian Harbison

Go to

Buy a USB to DSB 9-pin Male adapter

Product # 26886

after installing, check in device manager which Com port it has been assigned then set that in your programming software. If it sets a number above Com 5 reassign it, most programming software packages only use 1-4.

This is a big issue with most new laptops since they no longer come with COM ports
You will have to get a USB to serialconverter. Check with the PLC vendor which one they recomend, as not all types will always work. (there may be some timing issues)

There are several adapters for this needs USB to serial Cables or especial (and expensive) Ethernet to serial (or modbus, Rtu Ascii and other adapters ) From Exemys or other vendors. hope it helps

PLC programmer

U need a PS2 <-----> Com Converter easily availble in the markets!!!!!!! round about 5 $ to 10 $
If your notebook doesn't have serial port, I'm assuming it has at least a USB port. Most PLC's now have cables that can connect via USP port.

You need a USB-serial converter, a serial PCMCIA card, or somethign like that. PS/2 is pretty dedicated to mouse and keyboard.

If you have a PCMCIA slot, you could get a PCMCIA Cardbus Serial card such as the Koutech model CBS220-1 dual db9 serial card ($43 at Newegg). If you have USB ports, you could get a USB to RS-232 adapter, but not all of these work. One guy in the Intellution forum pointed out that the Keyspan model U19qi or HS19 adapters work with the PLC-5. Allen Bradley also makes a PCMCIA RS-485/DH+ card (called the PCMK card) that works well if you have a RS-485/DH+ based PLC, but is very expensive. Hope this helps.
Buy a USB/RS232 cable. Good luck!!! They sometimes work and sometimes do not. I have found the Omron one works very well but it is not cheap.