Direct Digital Controller
Direct Digital Controller fw 4.013 – Ed. 01/2013 79
4.4.1.13 Communication protocol selection
This option is used to set up the communication protocol that the DDC uses on the RS-232 and RS-485 serial
connection port.
As far as the RS-232 port is concerned, "PC Terminal” can be chosen if a link exists with a Personal Computer
provided with terminal emulation software. With this it is possible to give pre-set commands with the keyboard
and view the results on the terminal; if you select the Modbus RTU (v1.0 or v2.0) protocol, you will be able to
connect any appropriately configured Modbus Master to the DDC for data exchange (the DDC always works
as Modbus Slave), using this protocol (the difference between Modbus v1.0 and v2.0 concerns the mapping of
the Modbus logs; normally the most recent version is used (v2.0), however v1.0 is maintained for a question of
compatibility with older devices).
As far as the RS-485 port is concerned, the “PC Terminal” option is not available, while options Modbus v1.0
and v2.0 are available.
It is not possible to select a Modbus option for both ports: if a Modbus option is chosen for the RS-232 port,
the OFF option (no protocol) is automatically forced on the RS-485 port; on the other hand, selecting a
Modbus option for the RS-485 port, the “PC Terminal” option is forced for the RS-232 port.
The document describing the mapping and meaning of the Modbus logs implemented on the DDC is
available on request.
1 - Select
from the initial screen to gain access to the main menu.
2 - Select
to gain access to the System installation.
3 - Enter the installer password on the numerical keypad that appears on the display.
4 - From the drop-down menu select “DDC”.
5 - Turn the knob to scroll the cursor downward until "Select Communic. prot" is highlighted and press the
knob to access the screen.
6 - Select the required entry in the left column for RS-232, and in the right column for RS-485; for example:
• Select “PC Terminal” in the left column (RS-232) if you wish to communicate with a Personal
Computer with a terminal emulator, for example to download the events log. Select this also if you
must update the DDC software (operation reserved for authorised Technical Assistance Centres)
• Select a Modbus option (typically, Modbus v2.0) in the left or right column, if using a Master Modbus
connected respectively to the RS-232 or RS-485 port of the DDC. Robur WISE and Robur Monitor
devices require Modbus V2.0 to be set in the left column (RS-232)
4.4.1.14 Modbus address setting
This option permits to set the Modbus address, that is the address used by the DDC to answer the requests
coming from the Master Modbus. Please note that the DDC operates as a slave modbus . This has nothing to
do with the concept of Master and Slave between several DDC’s located on the same CAN; to all intents any
effect, the DDC can be either Master or Slave for the control of its unit on the plant.
NOTE
NOTE
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