The limit is 256 devices, however in most cases this will be too much. 

Also the machine should be powerful enough to support this amount of devices. 

We will start the process as soon as a device is connected. This will speed up the process and you will be able to connect a batch of devices while the first one is already busy processing.   

If you want to diagnose devices a workable amount will be 10. There is no need to connect more devices as you will need to do some manual tests.