Apple’s Thunderbolt-to-FireWire adapter is designed to attach legacy FireWire devices to a new Thunderbolt-equipped Mac without a FireWire port. This adapter requires a Thunderbolt-equipped Mac to function.
The adapter does not work in the reverse direction. It will not enable FireWire-only Mac systems to connect to any external Thunderbolt device.
If you have a Mac with only a FireWire or DisplayPort, it cannot be used with any Thunderbolt device; including Pegasus R Series, Pegasus2 R Series, Pegasus J Series, or SanLink family products.