Once a compilation error occurs during patch POU, the project must be compiled and downloaded again. Therefore, you need to stop the CPU. Please consider the following four points:
1) Add variables with AT specification (with addresses assigned). The reserve memory is consumed when adding variables

    with no AT specification (to which no address is assigned) to a program. Variables with AT specification do not consume the

    reserve memory.
2) Prepare variables for patch POU. When using existing variables in patch POU, the reserve memory is not consumed.
3) Increase the size of 'Reserve for POU'. By default, the non-retain memory is set to 10, retain memory to 10, and FB

    memory to 10. Increase these size to increase the number of patch POU you can perform.
4) Use 'Enable online change exceeding reserve size' function SPH3000 series and SPH2000 NP1PM-256H support the

    function that automatically secures the reserve memory to continue patch POU if the reserve memory is insufficient.