I would suggest you look at the data sheet for both the DF Robot part and the ADXL345 which it's based on. Usually with a 3-axis device like this you orient one axis (say, Z) along the gravity direction. Sometimes the device automatically compensates for gravity so that when it's mounted this way, the x and y axis outputs are zero at rest. If not, then you'll have to calibrate out the gravity term.
Thank you barry. I will study on this. For now, this is what i have from the IMU:
X: -0.16 Y: -0.59 Z: 8.67 m/s^2
X: -0.20 Y: -0.55 Z: 8.63 m/s^2
X: -0.12 Y: -0.59 Z: 8.63 m/s^2
X: -0.16 Y: -0.55 Z: 8.63 m/s^2
X: -0.16 Y: -0.55 Z: 8.63 m/s^2
X: -0.16 Y: -0.59 Z: 8.63 m/s^2
X: -0.12 Y: -0.59 Z: 8.63 m/s^2
X: -0.16 Y: -0.59 Z: 8.63 m/s^2
X: -0.08 Y: -0.55 Z: 8.63 m/s^2
X: -0.16 Y: -0.55 Z: 8.59 m/s^2
X: -0.12 Y: -0.59 Z: 8.67 m/s^2
X: -0.16 Y: -0.55 Z: 8.55 m/s^2
X: -0.16 Y: -0.59 Z: 8.59 m/s^2
X: -0.16 Y: -0.59 Z: 8.63 m/s^2
X: -0.12 Y: -0.63 Z: 8.67 m/s^2
X: -0.16 Y: -0.59 Z: 8.59 m/s^2
X: -0.12 Y: -0.63 Z: 8.55 m/s^2
X: -0.20 Y: -0.55 Z: 8.59 m/s^2
X: -0.16 Y: -0.55 Z: 8.55 m/s^2
X: -0.16 Y: -0.55 Z: 8.59 m/s^2
X: -0.12 Y: -0.59 Z: 8.59 m/s^2
But I'm not really sure why the z is not ~9.81 m/s. I will look in this matter also.
Thank you again.