In this paper, the cable tension and platform deflection of cable-driven robots are studied. The significance of cable density, elasticity, and cross-sectional area; platform mass, radius, and center of mass; the external wrench and platform orientation on the cable tension, platform deflection, and workspace of the planar cable robots is investigated. It is shown that, in addition to the cable mass, external wrench has a more prominent effect on the workspace of the catenary cable model. Moreover, design issues and parameters affecting the manipulator deflection are examined, and those that would result in disjointed workspace regions and deflection maps are identified. It is presented that the change in the deflection is gradual throughout the workspace for a constant external wrench. For the catenary model, depending on the cable properties, platform orientation, manipulator design, and external wrench, the workspace with the deflection limit may consist of disconnected regions.