Limitorque controlled by DDC-100M

Hi

We have number of 100 (addressed from 1~100) MOVs Limitorque controlled by DDC-100M series 90 -30 two net work controller hot standby net work configuration

Some times for unknown reason I have problem of communication loss for no of about 40 MOV we did reset MOVs individually from site one by one and sometimes we replace DDC comm. Cards randomly. 1, 2 days to do such job in .some rare we mange to put it back to normal.

So please any systematic procedure to follow . for example to check CPU, DDC cards, and which MOV can cause such problem in the loop i.e. start from where ?

Thankx