PLC I/O Fusing

Typically in 120 VAC PLC panels how can the code be correctly applied for fusing from a control transformer to loads such as electronic modules. One main fuse from the line side of the 120 VAC power supply and then branch fuses for each module is normally implemented. However if we have a module such as a 16 channel isolated DI card, is it required to fuse each input channel to protect each individual channel circuit ( assuming all channels have the same line and neutral ) ? Secondly do PLC vendors in general prefer to have fusing on individual I/O channels ( e.g., AB, , Schneider, Siemens)