Abstract: A railway car order selecting system in which data representing the positional order of the various cars of a train and other data is accurately communicated to a central station regardless of the particular arrangement of the cars. A selecting relay applies an input signal to one of plural data transmitting devices, one being located on each car, to select a front car of the train. Extension lines connected into a single line connect the data transmitting devices to one another and are used for selecting the car order. Logic circuits are provided for the extension lines to supply, in response to an output signal from the respective data transmitting devices, a supply voltage to the following data transmitting device. Selection of the front car in this manner results in starting the data transmitting devices on the following cars successively and registering the positional order of the following cars in the data transmitting device at the front car.