Fetch `PORT` data with `Rblpapi`

First get the portfolio id, which you get under PRTU<GO>. Append the string " Client".

getPortfolio("UXXXXXXX-X Client", "PORTFOLIO_DATA")
getPortfolio("UXXXXXXX-X Client", "PORTFOLIO_MEMBERS")
getPortfolio("UXXXXXXX-X Client", "PORTFOLIO_MWEIGHT")
getPortfolio("UXXXXXXX-X Client", "PORTFOLIO_MPOSITION")

To get the data for a specific data, set "REFERENCE_DATE".

getPortfolio("UXXXXXXX-X Client", "PORTFOLIO_DATA",
              overrides = c("REFERENCE_DATE" = "20170110"))