Analog:
You can continue to use your analog S7 plug head pH and redox electrodes with an adapter cable analog/IDS pH electrodes. A special adapter will soon be available for analog sensors with temperature probes.
Digital:
You can use all digital sensors with the above parameters (pH, ORP, conductivity, turbidity and oxygen).
Digital plug-in head sensors:
You can use all digital plug head sensors with the named parameters (pH, redox, conductivity, turbidity and oxygen).