Agricultural implements, such as variable rate input applicator, have to receive and transmit messages to other existing systems inside the vehicle. These messages must follow a rigid protocol to assure reliability regarding the delay times among messages and their responses and outcomes. The ISO 11783 protocol, or just ISOBUS, is a protocol that specifies the communication of agriculture tractors and its implements. Applications that deals with the ISOBUS protocol may reduce redundant equipment on the vehicle and its implements, hence reducing costs. However, many implements are not prepared yet to work over a protocol like ISOBUS natively. For them, it would be necessary to find a way to turn on and off their valves, read their sensors, still following the rules of a VRT protocol. A Programmable Logic Controller (PLC) is well known by its reliability in industrial applications and it could be suitable to fill this blank in Precision Agriculture. A PLC can communicate with other devices through the serial communication protocol Modbus RTU. Thus, to use a PLC together with an ISOBUS application an embedded system with a serial port for exchange Modbus RTU protocol messages is necessary. The embedded device can convert PLC data to ISOBUS needs and vice versa. This paper presents a case study on using a PLC to control an non-ISOBUS implement carried out on an Advanced Vortex 3000 sprayer with the arms divided in 4 independent segments, an Altus DU351 PLC communicating through the Modbus RTU protocol, a Topcon X30 Virtual Terminal, an Intel NUC mini-PC and the C++ ISOBUS library, IsoAgLib. Results show that using a PLC to control an implement in Precision Agriculture is possible and it is viable, because the measured delay times between each message, their responses and outcomes, show that using PLC Modbus RTU messages will not affect the entire process considerably.