I have four of these kits. Individually, they all work at all addresses (0-3). However, if I try to use them all at once. Card 0 and 1 are found and 2 and 3 are not. If I leave card 2 out, Cards 0, 1, and 3 are found. This is true regardless of which physical cards I use.
Is this an assembly problem, an card design problem, a DLL problem or something in my program?
Any help would be appreciated.
Does the same problem occur if you use the demo software K8055N_Demo.exe and click the “Search Devices” button?
Yes, the behavior is the same
Are the cards connected via separate USB HUB or are they all directly connected to the PC?
If you are using separate USB HUB, is there any difference if you connect it to other USB socket of the PC or if you connect some of the cards to the PC and some of them to the USB HUB?
Also what happens if you change the order of the cards connected to the USB ports?
Have you tried an active (powered) hub?
Interesting result. Was using a four port USB hub (powered). Cards 0, 1, & 3 work on the hub. Plugging Card 2 into the hub with them makes only Cards 0 and 1 work.
Leaving Cards 0, 1, & 3 on the hub, I plugged Card 2 directly into the computer and they all work.
Should I get a new hub? If so, do you have any recommendations (specs)?
I’m not sure this is strange.
Did you try moving card 2 to a different port on the hub.
Kind of sounds like the port on the hub may have an issue.
Even stranger, Now all four cards work on the hub !?!?!?!
Anybody want a copy of my four-card program?
This may be operating system related issue too.
It seems that the order of the cards connected to the ports of the USB HUB matters.
What operating system are you using?
Windows 10
OK.
This is indeed very strange problem - not reported before.
Anyhow, good to see that you got all the four cards working simultaneously.
Thanks for the support. I hope they keep working.
Any interest in my program. It is an extension of the demo program and can exercise all four cards at once. It can output various patterns too.
It would be nice to see your software.
Can you provide a link to download it?
The link works fine and your program works fine too 
Nice effects in the Output Test mode indeed!
This is very nice software to test up to four cards simultaneously.
Thank you!