6
Creating Project Files—SEAbus Port Expander
Siemens Energy & Automation, Inc.
47
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.
Communications Settings
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-Out
and 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.