A system for serially transmitting vital data includes first and second processors to determine first and second data, a serial communication apparatus to input third data and output serial data based upon the third data, and a memory having first and second ports accessible by the first and second processors, a first memory writable by the first processor and readable by the second processor, and a second memory writable by the second processor and readable by the first processor. The first and second processors store the first and second data in the first and second memories, cooperatively agree that the first data corresponds to the second data, and responsively cause the apparatus to employ: one of the first and second data as the third data, or parts of the first and second data as the third data, and output the serial data based upon the third data.