Communications Settings

6 Creating Project Files—SEAbus Port Expander

When 2-wire communications are being used, RTS must be looped back to CTS on the DTU side of the cable. This can be done on the RS232 side by looping pins 4 and 5 or on the RS422/485 side by looping 16 to 18 and 17 to 19. See Appendix D for wiring diagrams for your particular PLC, and whether it uses a 2-wire connection.

To select the checkbox, click on it with the mouse or, with the 2-Wire RS422 or RS485 Communications selection highlighted, press the spacebar. An “X” will appear inside the brackets when it is selected.

Press the Tab or Right Arrow key to move to the next field without selecting this checkbox.

Before changing any of these settings, consult your computer, modem, or RS-232/485 converter manual for the correct settings. To move between the commu- nications settings, press the Tab or Enter keys. To select a setting, use the Up or Down Arrow key to move to the desired setting and press the spacebar to change your selection.

RTS Control (Request to Send Control)

RTS Control selection is an option provided for modems or for RS-232/485 converters that require RTS to be active only while the DTU is transmitting to the computer.

•If RTS/CTS is selected, the DTU will activate RTS and wait until CTS is active before transmitting to the computer attached to port 1.

•If RTS Delay is selected, the DTU will activate RTS and wait for the specified delay time to pass before transmitting. When RTS Delay is selected, the program displays an entry box for the RTS delay time. Enter the time in milliseconds.

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.

To change the intermessage time-out, select Intermes- sage Time-Outand enter the value in milliseconds. Then press the Enter key.

Saving Port 1 Configuration Information

Once you have entered all the configuration informa- tion, select Save to save the configuration to the project file. Then select Ok or press the Esc key to close the configuration screen.

If you have changed the configuration and have not saved it to the project file, you will be prompted to either save or discard the changes.

Select Revert to return to the last previously saved configuration without saving any changes.

Siemens Energy & Automation, Inc.