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This is a question for a project I am working on involving an unusual use of some USB equipment. Please see the diagram.
Our existing setup consists solely of a single link between the device and the laptop - this is the USB-over-Cat5 link shown as the top link on the diagram.
Essentially, the 2nd line (the bottom one) is a redundancy feature that we are proposing to install (the 'splitter' will also be required to be added). We experienced a failure of one of the USB-over-Cat5 extenders on one occasion recently, so we now want the ability to be able to switch to a backup line in the event this happens again during a test (we are working in a test environment and simply stopping the test to replace a failed component and restarting is not an option).
I am unclear about the nature of how this might work and am hoping for some clarification. Do I need to:
a) Buy a USB peripheral switch that can be controlled remotely (e.g. https://www.startech.com/uk/Cards-Adapters/USB-2/Hub/4-to-1-USB-Peripheral-Sharing-Switch~USB421HS) which will so where the 3-way splitter is in my diagram?
b) Simply splice into a USB cable at the point of the split, do a bit of soldering, breaking out one cable into two?
c) Something else?
1The USB protocol only permits one Host per bus, so the soldering option is out. – I say Reinstate Monica – 2018-01-24T13:36:06.700
Unfortunately, it's not so simple. USB is not, and can not be, "split". Every USB hub is an active switching device (which is what the IC you'll find in them does). – Bob – 2018-01-24T13:37:16.980
As you're saying it's a test environment it should especially be supported to replace failed components. After all it's a test and not live environment. What motor controller is it? What options exist to connect to it? If you're switching manually anyway just change the cable physically on both ends? Is the motor controller a client or host for the adapters? – Seth – 2018-01-24T13:40:18.700
@Seth One reason this might not be practical to stop the test and replace failed components is if running the test takes a lot of time and is very expensive, and isn't primarily about computers. For example, the "Remote Location" might be a shed where they test giant gas turbines. Starting a turbine and running it takes a lot of fuel and time... a failed USB adapter in some of their diagnostic equipment is no good reason to waste all that time and money while replacing it. A backup makes good sense. – allquixotic – 2018-01-25T14:13:03.113
@allquixotic different definitions of test environment I guess. A test environment in IT usually is a place where its fine to break stuff. But good point to bring it up, didn't think about a different kind of test environment. – Seth – 2018-01-26T06:35:10.910