1. A support device for generating an executable program executed on a first programmable logic controller including a processor, a memory, and a network interface, the support device comprising: a first input unit configured to receive information defining, on a data-by-data basis, variables for data handled by the first programmable logic controller; a second input unit configured to receive a source program expressing processing executed on the first programmable logic controller using the defined variables; a third input unit configured to, when a first variable indicating first data handled by the first programmable logic controller is placed in correspondence, via a network, with a second variable indicating second data handled by a second programmable logic controller connected to the first programmable logic controller via the network, receive information that identifies a type of the second programmable logic controller in association with the first variable; and a generation unit configured to generate the executable program using the information defining the variables and the source program, wherein the generation unit adapts a data structure of the first data secured in the memory in correspondence with the first variable in accordance with the type of the second programmable logic controller.