The Well Logging Mobile Source Transit Security (WL-MSTS) Embedded Software Applications and Components described here are part of a system developed under funding from the National Nuclear Security Administration (NNSA) Office of Radiological Security (ORS). The objective of the system is to track mobile radioactive sources used in the well-logging service industry in support of oil and gas exploration. The individual software applications and libraries, and firmware executables work together and in conjunction with the electronic hardware components to provide situational awareness of the radioactive sources as they are transported from the home base of operations to a job site and back again. Information flows in near real time from the transport unit (over pack) carrying the sources to the end user's central monitoring center using satellite communications. A combination of active radio-frequency (RF) tags (attached to source shields) and radiation sensing is used to monitor the proximity of the radioactive sources to the transport unit. A Global Positioning System (GPS) is used to track the geographic location of the transport unit. Various sensors are used to detect and report tamper of the WL-MSTS Over Pack components. An embedded control panel/display is used to provide local status of the monitoring system to the authorized engineer and to allow the engineer to arm the system prior to transit and disarm the system at the job site or home base of operations. Base Station application software allows qualified personnel to track alarms, source information and source locations and provides contact info of individuals that need to be notified should anomalous conditions be detected. This report details the Master Control Unit Over Pack (MCU-OP) executable which is firmware configured for the Over Pack MSTS implementation.