See this paper for an Uncertainty Analysis for Pressure Modules (PMM) used in 6270A and 2271A Modular Pressure Controllers. A number of these modules can also be used in the 8270A and 8370A Modular Pressure Controllers.
Here's the link to the paper on the Fluke Calibration web site,
http://us.flukecal.com/literature/articles-and-education/pressure-calibration/application-notes/guide-determining-pressure-
Covers these models:
PM200
PM500 - added May 2018
PM600
PM630 - not yet included but same principles apply, pending update
BRM600-BA100K
See this document for 6270A Product Specifications
See this article for an example of calculating the uncertainty in absolute mode of an absolute PM600 module with the 1-year zero drift included, PM600 Absolute Mode Uncertainty - Understanding the RSS Formula
See this article if you're interesting in tracking the calibration coefficients of your module(s) over time, Q-RPT, AutoZero tracking sheet for absolute model Q-RPTs