S7 300 software redundancy problem

[cyrus]

Hi dears,

I did a s7 300 redundancy, change between CPUs will be done sucessfully but when cpu changed, output value of one DO module will be zero and true again. I want to know that it is possible in software redundancy that output value dont change during cpu change?

My digital output value is used for stop of compressor and must be true during running, when cpu master change to reserve cpu, for 1second this digital output value will be zero and true again and compressor will be stop. 

is it the principle of software reduncancy? Or its possible that digital value be frozen during change?

[sigmadelta]

One thing to confirm - look at the parameters of FC100 (SWR_START) and make sure your DO addresses fall in between the PIO_FIRST and PIO_LAST parameters.