Abstract: A device for testing connectivity is provided. The device includes a first connector including a contact pin and a spacer for biasing the contact pin away from a spring contact pin of a second connector, when the first connector is inserted into the second connector. The device also includes an indicator, coupled to the contact pin of the first connector, for indicating whether the contact pin of the first connector is in contact with the spring contact pin of the second connector.

Abstract: A device for testing connectivity is provided. The device includes a first connector including a contact pin and a spacer for biasing the contact pin away from a spring contact pin of a second connector, when the first connector is inserted into the second connector. The device also includes an indicator, coupled to the contact pin of the first connector, for indicating whether the contact pin of the first connector is in contact with the spring contact pin of the second connector.

Abstract: A device for testing connectivity is provided. The device includes a first connector including a contact pin and a spacer for biasing the contact pin away from a spring contact pin of a second connector, when the first connector is inserted into the second connector. The device also includes an indicator, coupled to the contact pin of the first connector, for indicating whether the contact pin of the first connector is in contact with the spring contact pin of the second connector.

Abstract: Stackable modules using infrared (IR) radiation for communication. Each module includes a housing with upper and lower holes and IR transceivers aligned with the holes. One of the two IR transceivers or transceiver sets detects IR communications through a lower hole and transmits through an upper hole, and the other detects IR communications through an upper hole and transmits through a lower hole. In this manner, the stackable module uses IR radiation to communicate with similar modules both above and below the module. The module further includes communication logic coupled to the transceivers to control communications between the transceivers of different modules. The module preferably includes a network device operating according to any desired network protocol. A stack network system includes a chassis with several slots, where one or more stackable modules are removably plugged into the slots of the chassis. Management may be distributed among the modules or centralized.