Can I use an external mag (GY-271) in pixhawk 2.1?

Hi,

Recently, I try to use an external compass (GY-271 and GY-273)

I found the GY-271 or GY-273 use hmc5883L.
So I tried to use it like that.

hmc5883 -C -T -X start

and the result is like that.

image

How can I use an external mag? Is it possible to use GY-271 or GY-273?