176 ï Application ExamplesExample of a Modbus TCP ServerWAGO-I/O-SYSTEM 750Linux Fieldbus CouplerThe Modbus addresses are:Register Read Access:Start address End address Description0x0000 0x01FF Inputs of the process image0x0200 0x03FF Outputs of the process imageRegister Write Access:Start address End address Description0x0000 0x01FF Outputs of the process image0x0200 0x03FF Outputs of the process imageThe dynamic loadable module "kbus.o" is used for the internal bus support.In addtition, kbusapi is used which makes it easier to access the internal busmodule. This API (Application Interface) is added to the program duringcompilation and linking. The API interfaces are also described in this chapter.The dynamic loadable module kbus.o serves to access the connected modulesfrom a user program environment. In order to illustrate the driver interface, theLinux coupler incorporates the kbusdemo example program. This program canread or write the state/data of the internal bus via the Linux console.Source code descriptionA more detailed description of the source code is not given now. The ModbusTCP server is only supposed to illustrate a more complex application on theLinux fieldbus coupler. Furthermore, the program is used to conduct afunctional test of the Linux coupler and is hence installed on every coupler.The customer can change or extend the source code arbitrarily.
