DO Meter Questions

[HopSteady]

What is the workflow for taking accurate DO measurements? I guess pouring a sample of carbonated beer into a glass and sticking the probe in won't cut it as it will be exposed to o2. Perhaps in-line during a transfer between fermenter to keg and at the keg liquid out post (although I don't see how the Extech would allow this)? Does carbonated beer need to be de-gassed and how is this best done without exposing it to o2? Is there a SOP or guideline posted anywhere? Thanks.