Siemens DTU3005-B - Manual (Page 37)

5
Creating Project Files—Modbus Master to Devices
Siemens Energy & Automation, Inc. 33
5.5 Modbus/Passthrough Setup—Port
3
Port 3 can be used for passthrough communications
to your Siemens SEAbus devices or for connection to
a second Modbus Master device. Passthrough com-
munications enables a PC running WinPM, or other
supervisory software connected to port 3 of the
DTU3005 to communicate directly with the SEAbus
devices connected to port 2. In passthrough mode,
any messages received on port 3 of the DTU are sim-
ply “passed through” to the devices.
Passthrough communications are not available for
VDEW devices; see Section 5.3 for Port 3 (Modbus
Master)
configuration of VDEW devices.
You must have a Modbus Master to Devices project
file open to configure port 3 using the instructions in
this section. Select Port 3 (Modbus/Passthrough) from
the Edit menu, and the Port 3 configuration screen
appears.
The first option on the configuration screen allows you
to choose connection to a second Modbus Master
device or passthrough to port 2. Select the appropriate
configuration with the mouse, or use the Up or Down
Arrow
keys to highlight the selection and press the
spacebar .
Modbus Master
If you select Modbus Master, the screen appears as
shown above. Select the Modbus protocol by select-
ing the Modbus Protocol list box, highlighting either
ASCII or RTU, and pressing Enter. After you have
selected your protocol, press the Tab key to highlight
the Modbus ID selection box. The Modbus ID is used
to identify which Modbus Master device the DTU is to
communicate with. Type in the Modbus ID number
and press Enter.
The remaining configuration selections are for the
communications parameters and have the same
choices as those for port 1. Refer to Section 5.3 for
instructions on these fields.