A Modbus TCP/IP developer designs, implements and maintains systems that communicate using the Modbus TCP/IP protocol, a standard for data transmission often used in industrial automation. They are responsible for creating server and client applications that can interpret and handle Modbus messages, ensuring data integrity and security. They must understand the specifics of the Modbus protocol, including message structure, error checking and addressing. They also troubleshoot and resolve issues related to network connectivity, data transmission and application functionality. Additionally, they may work with hardware devices such as programmable logic controllers (PLCs) that use the Modbus protocol.