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.

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Image 38
Siemens DTU3005-B manual Passthrough to Port 2 SEAbus, With the 2-Wire RS422 or RS485 Communications