View Full Version : 1761-CBL-PM02 / Optical Isolator

March 6th, 2004, 11:46 AM
Recently I bought a communication cable (1761-CBL-PM02) for MicroLogix controllers but there is Caution Tag on the cable package saying "An optical isolator is recommended between the controller and your programming device". I would like to know what this optical isolator is and whether I should use it. Any advice on this would be much appreciated.

panic mode
March 6th, 2004, 12:49 PM
Did you try to google or search this forum using
search phrase "optical isolator"?

June 20th, 2008, 10:36 PM
I know this thread is old but I am interested in the answer to the original post.

I am new to plc's and just bought rslogix 500 and I'm going to buy a micrologix 1000 to play around with.

A couple of quick questions:

1.I was searching for a 1761-CBL-PM02 cable on ebay and all I found were the non-factory made cables.Are these safe to buy or should I go with the more expensive Allen-Bradley cable?

2.Regarding the opto-isolator.Is there a part number you guys can give me for this.I dont want to fry my new laptop.

Thank you for the help

June 20th, 2008, 11:22 PM
Link for cables below or your local AB Rep


See PDF's below for isolator its called an 1761-NET-AIC

June 21st, 2008, 12:55 AM
More cables at link below.


June 21st, 2008, 07:51 AM
Thanks for the plug Mickey...

I am going to start selling isolators (I have about 50) but I have sent one to Dave (504bloke) to test for me before I start selling them

I think these are used primarily in the UK?? due to the voltages? I have never used one and don't think I will have the need... but I may be wrong

As far as my cables and mrplc (Chris) I test mine 100% before I ship them, I am sure Chris also does.

On the Micro's there is 24vdc on one of the pin, so if it was not made correct then you could smoke you com port, but this is why we test them.

Also if you are going to just play around then you may want to read this http://www.plctalk.net/qanda/showthread.php?t=33740&highlight=free+rslogix+500 it may save you a few bucks


panic mode
June 21st, 2008, 12:46 PM
never need one when programing MicroLogix but i have used them few times on PCs on the shop floor doing data logging etc. it resolved issues of PC freezing when port is in use (serial ports on some motherboards are very sensitive, specially newer ones where signal levels are lower). this is a shame and it should have been addressed by computer makers which is not likely to happen now when RS232 presence is fading away.

June 21st, 2008, 04:27 PM
I am going to start selling isolators (I have about 50) but I have sent one to Dave (504bloke) to test for me before I start selling them

Its still under test :)

The guy i gave it too has blown up 2 laptop serial ports so i think it will have a good test :) I will hurry him up next week !

Needed here when connected to an ssd drive 232 port as its not isolated.