the x axis controller of the robot transporting the pod the x axis controller responds goto done 604 to the clc controller when the movement is complete next the clc controller issues a goto upper travel zone 606 command to the z axis controller of the robot transporting the pod the z axis controller responds goto_done 608 to the clc controller when the movement is complete the clc next issues a goto buffer command 610 to the x axis controller and when the movement is complete the x axis controller responds goto_done 612 next the clc issues a goto disengage position command 614 and the robot positions itself just above the pod when the movement is complete the z axis controller will respond goto_done 616 the clc then issues a goto engage position command 618 and the robot positions itself at a level to engage the pod if a pod is present at the static buffer the z axis controller then issues a pod detected signal 620 followed by a goto_done signal 622 upon receipt of the pod detected signal 620 and goto_done signal 622 the clc will issue an engage_gripper command 624 when the clc receives the gripper_engaged signal 626 the clc will issue a goto upper travel position command.