sample time of input digital data

hi,

i am learning simulink and want to generate digital binary data with sampling frequency of 8khz.

when i use signal from workspace, i entered 1/8000 in the sample time box, but i am not getting signal in the scope.

is it correct to enter 1/8000 in the sample time box? if so why i am not able to see the digital data in the scope?

i can see the data when the sample time is set to 1.

thanks for help