USB to Serial and RSLinx

Tharon

Member
Join Date
Jan 2007
Location
Other
Posts
1,430
My old laptops had a PCMIA slot and a serial adapter for it. This card was always installed so the COM port was always installed on my computer, even if I unplugged the cable. RSLinx was happy.

Now my new laptops have to use USB to Serial adapters. When ever I plug/unplug the adapter windows installs/uninstalls the device. If RSLinx is open and the USB adapter is uninstalled and installed again, RSLinx won't recognize the COM port until the program is shutdown and restarted.

This doesn't cause me any problems. I just always make sure to close RSLinx completely before unplugging the device. But it causes headaches for some of my coworkers (and then by extension me) who need to use it and can't figure out why RSLinx isn't working.

Is there a way to force windows to keep a USB device installed even if it's disconnected (obviously won't be able to use it disconnected, but I don't want the COM port uninstalled while RSLinx is open). Even if it means that USB port is locked out of use by other devices, that'd be fine.

Thanks in advance.
 
I've seen devices that reinstall the driver (and claim another COMx number) every time you plug them into a different USB port, but never one that reinstalls the driver when you plug it into the *same* port.

Is it possible you have some sort of user account privileges setting that won't allow a hardware change to be permanent ?

Can you post the make and model of USB/RS232 interface ? The Forum favorite is the Keyspan USA-19HS.
 
The USB-Serial adapter is the 9300-USBS from Allen Bradley. I've used multiple others as well and run into the same issue. So far RSLinx doesn't have any problems with any of the adapters themselves. Some of my other PLC programs (Siemens, etc) don't like some, but RSLinx has been very forgiving.

What I meant when I said it uninstalls/reinstalls the device is when I connect/disconnect the device it appears/disappears from my hardware manager (under computer properties). Once it disappears, RSLinx will not recognize it again until I restart the program.

What I wanted to do is force windows to keep that COM device alive, even though it can't use it, in hopes that it would eliminate the issue with RSLinx losing track of that COM port. I'm not even sure if it would work, but it's just something I wanted to try.

Edit:
Added a couple screenshots.
I'm not even sure if this is possible. I can't even think of what to call it to search for the answer properly.

Not Plugged In.jpg Plugged In.jpg
 
Last edited:
All you have to do in RSLinx is go to Configure Drivers, select the DF1 driver you are using for your USB-Serial converter, and click "Stop", then "Start", and it should be ready to start using the driver again.

You should always make sure with USB converters to select a designated physical USB port you will use and to ONLY plug the converter into the same USB port, otherwise you can end up with multiple drivers/ports for the same device.
 
You should also change the port number from anything other then COM1 to COMx, I have had a lot of phone calls that this simple change has worked

Make sure.... you have the cable plugged before you start RSLinxs, if you start Linx first it will look for the cable and will lock out in conflict, as Brendan said you can also stop and re-start

The USB port com number on the cables I manufacture are reserved after you install them once... so if it shows as COM5 it will be COM5, but remember this is hardware so by unplugging it you are removing your hardware so your PC can't keep it installed (unless it is plug in)

Hope that helps
 
If you don't already do this, always use the (safely remove USB device)
icon on the taskbar ......before removing the USB adapter.
 
If you don't already do this, always use the (safely remove USB device)
icon on the taskbar ......before removing the USB adapter.

I think this was true with XP but not necessary Windows 7, wonder how Windows 8 will be :)
 

Similar Topics

Until recently, I haven't had to connect to a piece of hardware using a serial connection in quite sometime. Well, that all changed yesterday when...
Replies
33
Views
6,167
I have VMs with XP, but I sold an old laptop and 32 bit USB to Serial Converter to a customer who needed it. I went back to a known supplier for...
Replies
12
Views
3,031
Good Morning , I just purchased a Windows 10 Hp Laptop. Of course no serial ports , but 3 USB ports . Need a USB to Serial cable to go to...
Replies
20
Views
6,018
Dear experts, I can't connect to Siemens s7 200, I have Siemens ppi cable but I don't have serial port on my pc so I used serial to usb converter...
Replies
11
Views
4,455
Hello all, recently bought a Keyspan Tripp Light 19HS USB to Serial adapter, due to the recommendations of a few people here on the forums. Its...
Replies
12
Views
4,186
Back
Top Bottom