# Trouble connecting to AB PLC



## JRaef (Mar 23, 2009)

The RS-232 port emulators that connect to USB ports in newer PCs are tricky. The port address changes every time you connect it up. So the trick is that you have to connect it, THEN go into your system settings and SEE what port number it was assigned to, then go into your software and make sure they match. So for example the first time you connected it, the "RS-232 port" was Port 4, then you set your software to say it was using Port 4 and all was good. but when you changed to the other PLC, the USB port was reassigned as Port 6, then your software is still trying to talk out of Port 4 and there is nothing there. it's a PITA we all had to learn about the hard way when PC mfrs stopped putting in RS-232 ports.

If you have a Logix PLC, you can get a direct USB adapter cable, called an "Anaconda" cable now. But given that you say the PLCs are networked via DH+, that means they are old and you are going to have to figure this one out. Like I said, it's a PITA.

PS:
That brings up another issue. BECAUSE this is an older system, the software will probably only support 4 ports, Comm 1 through Comm 4. If the USB driver assigns it to Port 5 or 6, it doesn't work no matter what, because your software will not allow you to change to anything above 4. So what you do then is to go into the Properties of the USB adapter and manually set the Comm Port Address to 4.


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## Jlarson (Jun 28, 2009)

We have one brand adapter that likes to go into double digit COM ports and that always screws with older software. 

I dread usb-serial adapters, had our HP probooks ordered with real serial ports.


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## JRaef (Mar 23, 2009)

Jlarson said:


> We have one brand adapter that likes to go into double digit COM ports and that always screws with older software.
> 
> I dread usb-serial adapters, had our HP probooks ordered with real serial ports.


That's getting harder and harder to get now. I just ordered a new Dell, it was no longer an option, even if I wanted to wait.


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## Jlarson (Jun 28, 2009)

JRaef said:


> That's getting harder and harder to get now. I just ordered a new Dell, it was no longer an option, even if I wanted to wait.


Yeah it was several weeks and a couple hundred extra last one we got. 

From now on we'll probably just buy old panasonic toughbooks with ports at auction and upgrade them.


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## Dock (Sep 24, 2014)

I've found that if I use the same real world USB port each time the issue is less of a problem, the assigned port seems to stay the same the majority of the time. My think pad has three ports. I actually went as far as labeling each port for the com setups I use most so I can remember which one I used last because of this exact issue.


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## Calectrical (Oct 19, 2010)

What If I get a 1747-uic cable and connect via dh485 instead of the rs 232.


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## triden (Jun 13, 2012)

Are they SLC's? If so, what model?


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## Calectrical (Oct 19, 2010)

Yeah they are both slc 5/03 cpu's.


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## triden (Jun 13, 2012)

SLC 03 processors are not DH+, they are only RS485 and DF1. The one you cannot connect to sounds like it has a 1747-AIC and a 1747-KE card attached to it. Plug your pc directly into the serial port on the CPU. Make sure you have the right com port connected in RSLINX and use the Auto-Configure feature. Option two would be to plug into the bottom serial port on the KE card, but you will have to setup your driver in RSLINX to talk to the KE instead of the SLC. 

I don't like the UIC cable...always gives me troubles


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## glen1971 (Oct 10, 2012)

I've had pretty good success with these, when I didn't have a serial port on my laptop..

http://www.tripplite.com/high-speed-usb-to-serial-adapter-keyspan~USA19HS/


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## Calectrical (Oct 19, 2010)

How do I set up rs linx to talk to the ke drive?


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## triden (Jun 13, 2012)

Choose DF1 and then choose KE in the dropdown where you configure your port. I don't have it in front of me, but its almost the same as setting up the SLC/03.


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## Paulusgnome (Mar 28, 2009)

Had some success lately with a 1761-UIC connecting to a SLC45/02 using DH-485 but I can't say it was simple or problem-free. If I hadn't been able to tap into the experience of a former colleague who used to know this stuff backwards, we would have been stuffed. 
If I could drop this old serial-port junk in the trash and replace it I cheerfully would, but needs must when the devil drives.


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