Embodiments of the present disclosure provide method and device for providing service for a programmable logic controller (PLC), including: creating a virtual-functional-module-description file including an address of an input channel of a virtual functional module to be created; and creating the virtual functional module in a PLC based on the virtual-functional-module-description file, assigning the address to the input channel of the virtual functional module, and creating a virtual-functional-module-configuration file including a mapping relation between the input channel and an output of a service provider. The present disclosure proposes a concept of a virtual functional module which is used to map data provided by intelligent data sources outside the PLC to input channel of PLC so that the data can be the same as normal input values used by PLC program.