How to contact a button on my serial port device?

Hello,

I have to read some data out of my measurement device.
But the problem is that I dunno how to send a request that has the same
function as a button on my device.
So how can I check which button on my device sends which code?
It is a Color Measurement devce from Konica Minolta called CL-200.

Or is there an other way to get the data out of the device up to my pc?
(But it has to be controlled by my PC not by button pressing on the device)