OpenHAB1/2 Nilan heatpump

Which newer openhab version… 2.4 ?
In that case, you´ll need to start all over, cause the old modbus binding is no longer supported in openhab 2.4. You need to use the new modbus binding, which requires alot of changes to your seup…

This thread might give you a clue:

In this thread you´ll be able to follow my transistion from old modbus to the new one with my Nilan Comfort 300LR (Ventilation system), with CTS602 interface.