Mitsubishi Electric MELSEC iQ-R Series Configuration Manual page 68

Setting the number of slots
The number of slots for each base unit can be set within the range of 1 to 12. Set the number of slots for the following
purposes.
• To secure slots so that the base unit can be changed to the one having the different number of slots in the future
• To keep the same number of slots even after the base unit used in the existing system is changed
[Navigation window]  [System Parameter]  [I/O Assignment]  [Base/Power/Extension Cable Setting]
2 ASSIGNMENT FOR MODULES
66
2.1 Slot Numbers on a Base Unit