Siemens DTU3005-B Passthrough to Port 2 SEAbus, With the 2-Wire RS422 or RS485 Communications

5 Creating Project Files—Modbus Master to Devices

Passthrough to Port 2 (SEAbus)

If you select Passthrough to Port 2 (SEAbus), the screen appears as shown below.

2-Wire RS422 or RS485 Communications	To change the intermessage time-out, select Intermes-
After you have selected Passthrough to Port 2 (SEA-	sage Time-Outand enter the value in milliseconds,
	then press Enter.
bus), press Tab or select 2-Wire RS422 or RS485 Com-
munications. This box will only need to be checked if	Saving Port 3 Configuration Information
the communications with your SEAbus devices use a
	Once you have entered all the configuration informa-
2-wire RS485 or RS422 interface. This is the usual
method of connecting SEAbus devices. When 2-wire	tion, select Save to save the configuration to the
communications are being used, RTS must be looped	project file. Then select Ok or press the Esc key to
back to CTS on the DTU side of the cable. This can be	close the configuration screen.
done on the RS232 side by looping pins 4 and 5 or on	If you have changed the configuration and have not
the RS422/485 side by looping 16 to 18 and 17 to 19.
See Appendix D for wiring diagrams for your particu-	saved it to the project file, you will be prompted to
lar PLC, and whether it uses a 2-wire connection.	either save or discard the changes.
To select the checkbox, click on it with the mouse or,	Select Revert to return to the last previously saved
with the 2-Wire RS422 or RS485 Communications	configuration without saving any changes.
selection highlighted, press the spacebar. An “X” will	Other Configuration Information
appear inside the brackets when it is selected.
Press the Tab or Right Arrow key to move to the next	The remaining configuration selections are the same
	as those for port 1. Refer to Section 5.3 for instructions
field without selecting this checkbox.
	on these fields.
Intermessage Time-Out
The DTU3005 uses the intermessage time-out to
determine when a complete message has been
received on the passthrough port. Once the first char-
acter of a message has been received, if the amount of
time specified by the intermessage time-out passes
with no additional characters being received, the
DTU3005 will consider the message to be complete
and process it.

34 Siemens Energy & Automation, Inc.