B&B Electronics GW-7553 - Manual - Manual (Page 22)

GW-7553 PROFIBUS/Modbus TCP Gateway User Manual (Version 1.00, Dec/2008) PAGE: 22
In section 3.1 and 3.2, we can understand that data exchange is through DI、
Figure 22 GW-7553 (master mode) communication protocol transfers
3.3 Communication protocol transfer
DO、AI、AO memory space of the GW-7553 between PROFIBUS Master、
Modbus and the GW-7553. When the GW-7553 acts as a Modbus Master device,
the data exchange runs continuously between PROFIBUS Master、Modbus and
the GW-7553, as shown in figure 22
、 23.