User Manual
Universal Serial/PROFIBUS DP Gateway
GT200-DP-RS
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20
5 Working Principle
The GT200-DP-RS has an input buffer and an output buffer. The data transmission between serial devices and
PROFIBUS DP master through GT200-DP-RS is established by mapping address.
5.1 As Modbus Master
When the serial interface of the GT200-DP-RS is configured as Modbus master:
The data read from Modbus slave devices by function code 01, 02, 03 or 04 is stored in the input buffer then
transmitted to PROFIBUS DP master. The data written by PROFIBUS DP master is stored in the output buffer,
then sent to the Modbus slave devices bu function code 05, 06, 15 or 16.
* Every address corresponds to one byte.
GT200-DP-RS
Input Buffer
GT200-DP-RS
Output Buffer
0000H
4000H
0001H
4001H
0002H
4002H
0003H
4003H
0004H
4004H
0005H
4005H
...
...
5.2 As Modbus Slave
When the serial interface of the GT200-DP-RS is configured as Modbus slave, it allows a Modbus master
communicates with user’s PROFIBUS DP master.
The data is stored in GT200-DP-RS’s input buffer and output buffer first.
For the Modbus master, the input buffer can be regarded as Coil Status (0x) area and Holding Register (4x) area.
The data of the input area can be read by function code 01 or 03, and can be written by function code 05, 06, 15 or
16. The PROFIBUS DP master reads the data in the input buffer.
Modbus Slave
Devices
PROFIBUS
DP Master
PROFIBUS
DP Master
Modbus Slave
Devices
