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 receiver configured to receive information defining variables and data types corresponding to the variables for data handled by the first programmable logic controller; a second input receiver configured to receive a source program generated by the support device expressing processing executed on the first programmable logic controller using the defined variables and data types; a third input receiver 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 generator configured to generate the executable program using the information defining the variables and the source program, wherein the generator 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.