Industry 4.0 manufacturing environments demand flexible automation systems capable of adapting to evolving production layouts and diverse operational requirements. Mobile manipulators that integrate omnidirectional bases with multi-degree-of-freedom serial arms address this demand; however, the coordinated control of simultaneous base locomotion and arm manipulation remains a significant engineering challenge. This paper presents MecaXarm, a modular ROS 2-based software framework for an omnidirectional mobile manipulator comprising a four-wheel mecanum-drive base and a six-degree-of-freedom industrial arm. The framework incorporates a modular five-package software architecture for rapid prototyping, a web-based human-machine interface for real-time operator monitoring, and a coupled kinematic control scheme based on a nine-degree-of-freedom extended Jacobian formulation using Resolved Motion Rate Control. The coupled controller is validated through Gazebo simulation via simultaneous execution of base lemniscate and end-effector Lissajous trajectories, achieving sub-millimeter mean end-effector tracking accuracy (0.18 mm) with the base locked and low-millimeter accuracy (2.16 mm mean) during coupled base–arm operation. A dual controller-manager architecture facilitates seamless transition from simulation to real hardware by isolating heterogeneous communication protocols. The results demonstrate that commercial off-the-shelf components integrated through open-source ROS 2 tools can deliver a validated mobile manipulator framework suitable for flexible manufacturing applications consistent with Industry 4.0 principles.