Modbus Slave & Modbus Master in S7 Refer to the Modbus Serial Pack v2 zip. Project Modbus v2 Manuals for drivers and hardware Preperation Preparation. To enable the Modbus functionality of the CP cards, you must do three things: Install Point to Point software from Install Modbus Master and Slave drivers from Fit the Modbus dongle to the rear of the CP Install the driver to the CP Preperation Summary of the GOULD-MODBUS Protocol The type of data exchange between MODBUS systems is controlled by Function Codes (FCs).