This paper reports the results of numerical investigations of the modal behavior of an external cavity diode laser device composed of a semiconductor laser and a distant Bragg grating, which provides an optical feedback. Due to the influence of the feedback, the laser device can operate at of various dynamic modes. The numerical calculations are based on the solution of the homogeneous coupled-wave equations using a transfer function approach. We show that the number and stability of laser modes is closely dependent on the material and device parameters such as transmission and reflection coefficients of the laser facets and sectional lengths.