LS7366R Quadrature Counter Count Disable

Hi,

I have a Due with an encoder shield that is counting pulses from an encoder... Working great.

However, I need to be able to disable the counter programmatically to stop counting even while the encoder is spinning (using my attached Touch LCD) .

The LS7366R's MDR1 register can disable counting by setting the bit 2 to 1 but I dont know how to do this within Arduino and the documentation is very hard to understand.

Any help or hints would be great!

Thanks