"IORD_8DIRECT" reads 32 Bit ?

Here is what I would do to work around your problem:

Did you create a custom SoPC builder component or connect the component directly to an avalon tri-state bridge?

Regardless, you need to configure your component as a 32-bit wide component. Let SoPC builder think that your external component is 32-bits wide. Then you can access it with any of the macros. You of course will only connect the lower 8-bits and disregard the upper 24. And of course you will do nothing with the upper 24-bits of data when you perform a read.

This guarantees only one access to the peripheral each time the NIOS performs a read.

Jake