Communication error (S5 -115 U) -308-3UA12 Expansion Unit interface module and et 100u

My hardware configuration is one 115 u cpu get I/O from 2 remote stations(ET 100U Distributed I/Os ) . This 2 remote stations (ET 100u) connect with separate 2 serial links via 308-3UA12 Expansion Unit Interface Module .

my fault is I can not operate these 2 et 100 u stations simultaneously .At one time this can operate only one.This means i stop one manually by ON/OFF switch ,then other station can ON.Then i ON the off station,there blink I/O disable bulb in red. Here I attach i stack and B stack and hardware configuration.

Communication error with 308-3UA12 Expansion Unit Interface Module and ET100u

SIR  ;

My hardware configuration is one 115 cpu u get I / O from 2 remote stations (ET 100 Distributed I / Os). This 2 remote stations (ET 100u) connect with separate 2 serial links via 308-3UA12 Expansion Unit Interface Module. 

 my fault IS I can not operate  2  et100 u stations Simultaneously .At one time this can operate only one.This Means i stop one manually by ON / OFF switch, then other station can ON.Then i ON the station OTHER off station there flashing I / O disable bulb in red. Here I attach i stack and B stack and hardware configuration .

My understanding figure is erase eprom program on 308-3UA12 Expansion Unit Interface Module  .Can it happen ..???sir ..

Can u send me sir COM ET 100 communication software ??? I cant find this software from internet.