At the ready and Up on

At the ready adjective - Ready for immediate use.

Up on and at the ready are semantically related. In some cases you can use "Up on" instead an adjective phrase "At the ready".

Up on adjective - Being up to particular standard or level especially in being up to date in knowledge.

At the ready and up on are semantically related. Sometimes you can use "At the ready" instead an adjective "Up on".