An article of manufacture, an apparatus, and a method for determining an extended measurement word at a channel subsystem of an I/O processing system using data from a control unit are provided. The article of manufacture includes at least one computer usable medium having computer readable program code logic. The computer readable program code logic performs a method including sending a command message to the control unit, and receiving a transport response information unit message at the channel subsystem in response to sending the command message to the control unit. The computer readable program code logic additionally extracts a plurality of time values from the transport response information unit message as calculated by the control unit, calculates an extended measurement word as a function of the time values, and writes the extended measurement word to computer readable memory in the I/O processing system.