Is it possible to connect a slave device with SSI to master with I2C/SPI?

I have a National Instruments USB-8451 controller that needs to work with an AMO encoder. The NI controller supports I2C and SPI. The encoder supports EnDat, Fanuc, SSI, and TTL. I believe that logically, I2C and SSI may be compatible.

Is my assumption correct? Is it possible to connect the two devices?

Thanks!

AMO encoder data sheet USB-8421 data sheet

The problem was solved with a custom physical adapter.