A relay and metering test instrument (100, 300) comprising: an application processor circuitry configured to control functional operation of the relay and metering test instrument, the application processor circuitry further configured to receive a source code state program selected by a user, and operational parameters received as inputs from the user, the application processor circuitry configured to compile the source code state program and the operational parameters into a test routine (130; a memory circuitry in communication with the application processor circuitry, the application processor circuitry configured to store a plurality of other test routines and the test routine in the memory circuitry; a real time processor circuitry in communication with the memory circuitry, the real time processor circuitry configured to selectively and independently execute the test routine or one of the plurality of other test routines to perform a plurality of respective test states; and an input/output processor circuitry in communication with the real time processor circuitry and the memory circuitry, the input/output processor circuitry cooperatively operable with the real time processor circuitry to output test signals and monitor for receipt of input test signals according to execution of the test routine; characterized in that the relay and metering test instrument (100, 300) is configured to deploy a parameters-altering algorithm without requiring an update to the firmware in the relay and metering test instrument; and that the real time processor circuitry is operable for execution of the parameters-altering algorithm during the execution of the test routine, and that the application processor circuitry is operable for executing the firmware in the relay and metering test instrument to control functional operation of the relay and metering test instrument. an application processor circuitry configured to control functional operation of the relay and metering test instrument, the application processor circuitry further configured to receive a source code state program selected by a user, and operational parameters received as inputs from the user, the application processor circuitry configured to compile the source code state program and the operational parameters into a test routine (130; a memory circuitry in communication with the application processor circuitry, the application processor circuitry configured to store a plurality of other test routines and the test routine in the memory circuitry; a real time processor circuitry in communication with the memory circuitry, the real time processor circuitry configured to selectively and independently execute the test routine or one of the plurality of other test routines to perform a plurality of respective test states; and an input/output processor circuitry in communication with the real time processor circuitry and the memory circuitry, the input/output processor circuitry cooperatively operable with the real time processor circuitry to output test signals and monitor for receipt of input test signals according to execution of the test routine; the relay and metering test instrument (100, 300) is configured to deploy a parameters-altering algorithm without requiring an update to the firmware in the relay and metering test instrument; and that the real time processor circuitry is operable for execution of the parameters-altering algorithm during the execution of the test routine, and that the application processor circuitry is operable for executing the firmware in the relay and metering test instrument to control functional operation of the relay and metering test instrument.