Troubleshooting daisy-chained peripherals in OS X

While most Mac systems come with multiple USB, Thunderbolt, and firewire ports (for older systems), you may find yourself needing to daisy-chain your devices to get them all connected to your Mac. This may be simply because you are out of ports and need to use a hub or similar setup to give yourself more ports, or you may simply find it convenient to connect all devices to one port.

This may especially be the case with portable systems, where you have perhaps one or two USB ports, or maybe have used a Dock system such as the Matrox DS1 or the Belkin Express Dock with all your peripherals attached, and then pipe them all to your system through one Thunderbolt connection.

In some cases, even if you have a system like the late-2013 Mac Pro that comes with many USB, Thunderbolt, and FireWire ports, you might find yourself not wanting to access its back panel, and instead might find yourself daisy-chaining devices together, simply out of convenience.

With these setups, sometimes you might find problems occur in the chain of devices. This may be a hard drive suddenly being ejected, or a printer not working properly, which can happen to a single device in the chain, or suddenly to multiple devices at the same time.

If such problems happen to your peripherals, then there are several approaches you can take to isolate the problem and fix it:

  1. Check each device
    Attach each device you use directly to the computer, and try using it as the sole peripheral attached to the system. This will let you know if the device is working properly. If not, then you may need to have it serviced or replaced.
  2. Try different USB ports
    While some Macs only come with one USB, Thunderbolt, or FireWire port, others have multiple ports. While rare, it is possible one port may not be working properly either in software, or in hardware. In some cases, internal components of Apple’s systems such as keyboards, trackpads, memory card readers, and iSight cameras are USB devices that might be shared on the same bus as one of the external USB ports. If for some reason there is a conflict between these devices and an external device on the same bus, then one port may not work for the external device while another will.
  3. Check your cabling
    USB, Firewire, and Thunderbolt cables should seat firmly into their sockets, but sometimes an obstruction can get into the port and prevent a cable from seating properly. Therefore, check each to ensure no dirt or object are in any cable connector or device port that is being used. In addition, the cable itself may have a flaw in it, so try swapping it out with another one to see if that helps.If you are using exceptionally long cables and poor quality ones, then keep in mind that the connection protocol being used may not be able to communicate along it. This may especially be true if, for example, you are using a Therefore, try using a shorter cable. Shorter cables can get away with using poorer manufacturing, as they do not need to preserve the fidelity of the signal transferred along them as much.
  4. Check device power
    Sometimes a device in the middle of a daisy-chain, may demand more power than what the system has available. In these cases, the middle device may lose power and go offline, and with it take down all the devices in line behind it. If this happens, then you may see a number of devices randomly go offline at once.To correct for this, you will have to compensate for the loss in power. This can be done by using an external power supply for devices that can run on either bus power or external power. You can also use a powered USB or FireWire hub down the line, to provide a means of boosting power for the devices that are attached to it.
  5. Reorder devices
    While you technically can connect FireWire and Thunderbolt devices in any order, its preferable to have the ones that draw most power, or which are most important, be connected first in any daisy-chain line. For instance, if you have a Thunderbolt storage array and a Thunderbolt monitor connected to your computer, then be sure the array is in line before the monitor. In addition to reordering devices, be sure to use up as many of the computer’s local ports as possible, before daisy-chaining. For example, if you have two thunderbolt ports on the computer, then use one for the array and the other for the monitor, as opposed to leaving one port open while daisy-chaining the devices.As you add more devices to your system, you may have to prioritize them differently, but by spreading the load among different ports, you will greatly increase the stability of the connections to your system.
  6. Use a hub
    While a hub can be used to boost power in a daisy-chain, a better approach is to avoid long daisy-chains and instead connect as many devices you can to a single hub, and then attach that hub to your computer. This will ensure that you use the simplest approach to getting all of your devices connected, and do so in a way that few are relying on each other for proper connection.


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