A system comprising a robot and a multiplex device, wherein the robot is configured to perform work based on operation of a movable section (25, 27) and transmit data related to the work using the multiplex device, the multiplex device comprising: a multiplex connecting section connected to a movable side multiplex device, the multiplex connecting section being configured to transmit a position signal outputted from a position signal output section connected to the movable side multiplex device by multiplexing communication with the movable side multiplex device; an amplifier connecting section connected to a position signal output section amplifier, the amplifier connecting section being configured to transmit the position signal to the position signal output section amplifier, characterized by a measuring device connecting section connected to a position signal measuring device, and a switching section configured to switch from a connection between the multiplex connecting section and the position signal output section amplifier, and a connection between the multiplex connecting section and the position signal measuring device in accordance with detection of a connection between the measuring device connecting section and the position signal measuring device. wherein the robot is configured to perform work based on operation of a movable section (25, 27) and transmit data related to the work using the multiplex device, the multiplex device comprising: a multiplex connecting section connected to a movable side multiplex device, the multiplex connecting section being configured to transmit a position signal outputted from a position signal output section connected to the movable side multiplex device by multiplexing communication with the movable side multiplex device; an amplifier connecting section connected to a position signal output section amplifier, the amplifier connecting section being configured to transmit the position signal to the position signal output section amplifier, characterized by a measuring device connecting section connected to a position signal measuring device, and a switching section configured to switch from a connection between the multiplex connecting section and the position signal output section amplifier, and a connection between the multiplex connecting section and the position signal measuring device in accordance with detection of a connection between the measuring device connecting section and the position signal measuring device. a multiplex connecting section connected to a movable side multiplex device, the multiplex connecting section being configured to transmit a position signal outputted from a position signal output section connected to the movable side multiplex device by multiplexing communication with the movable side multiplex device; an amplifier connecting section connected to a position signal output section amplifier, the amplifier connecting section being configured to transmit the position signal to the position signal output section amplifier, characterized by a measuring device connecting section connected to a position signal measuring device, and a switching section configured to switch from a connection between the multiplex connecting section and the position signal output section amplifier, and a connection between the multiplex connecting section and the position signal measuring device in accordance with detection of a connection between the measuring device connecting section and the position signal measuring device.