is not saving to stl in ascii format

Dear all,

I have converted a xyz point cloud data points to mesh using Poisson surface reconstruction. When I save this in stl format using, it write only in binary format. I also gave (write_ascii = True) option, but still it writes in the binary format. What problem am I doing?

Below is the reference code used for meshing.

from stl import mesh
import copy

pcd ='')

# To obtain consistent normal orientation


# Or to flip normals to make the point cloud outward, not mandatory
pcd.normals = o3d.utility.Vector3dVector(-np.asarray(pcd.normals))

# Surface reconstruction using Poisson reconstruction

mesh, _ = o3d.geometry.TriangleMesh.create_from_point_cloud_poisson(pcd, depth=9)

mesh = o3d.geometry.TriangleMesh.compute_triangle_normals (mesh)
# paint uniform color to better visualize 
mesh.paint_uniform_color(np.array([0.7, 0.7, 0.7]))

#o3d.visualization.draw_geometries([mesh])'mesh176ascii.stl', mesh, write_ascii = True)

It still writes in binary format. Any leads will be appreciated.

Sunag R A.