The new CPU 412-3H will supplement the existing CPUs at the lower end. The performance (processing speed) of the existing CPUs will be improved, the work memory enlarged and some new functions added.

New functions (all CPUs):

Firmware updating during Run mode of the system, i.e. without process interruption
Firmware updating via network
SFC78 for load recording of the execution levels
SFC109 to set protection level 2 of the CPU (key switch replacement)
As is already the case with the CPU 414-4H and CPU 417-4H, the new CPU 412-3H will permit operation as F/FH system.

Compatibility
The new CPUs S7-400H V4.5 have a new hardware with a new operating system. The existing hardware cannot be upgraded to the new version and the new operating system V4.5 will only run on the new hardware.

The new CPUs are largely compatible with the current H CPUs. This means that user programs written for the existing CPUs will also run on the new CPUs. However, mixing of new CPUs and current CPUs will not be possible.