Final answer:
In ROBOTC, the VEX Communication Mode should be set to 'Competition [VEXnet]' when testing the competition program through the Programming Hardware Kit.
Step-by-step explanation:
When using ROBOTC to program a robot for a VEX competition, the appropriate communication mode must be set to ensure the program can communicate with the competition controllers. In the case of testing your program through the Programming Hardware Kit, ROBOTC should have its VEX Communication Mode set to Competition [VEXnet]. This setting allows the robot to connect with the field's competition control system and the VEXnet keys for wireless communication during actual competition matches.