G 3800 X036 Operation Manual
August 2006
88
© 2006 Carlo Gavazzi Industri A/S. All rights reserved
4. Communication Ports
4.1. General
The Mastergenerator is equipped with 3 serial communication ports, which can be used for configuration,
communication with external devices and for networking of Mastergenerators. The two RS232 ports, COM1
and COM2, are accessible via two DB9 connectors in the front of the module, while the RS485 port is
accessible through screw terminals. For pin-outs and technical details, please refer to the Mastergenerator
datasheet. All three ports can be used simultaneously.
4.2. Protocol
The protocol used for all serial communication between the Mastergenerator and external devices is the
Modbus protocol. The format of this protocol can be found on the homepage www.modbus.org. By using this
protocol, the following functions can be performed:
• Read the digital output status of Dupline addresses (status of receivers)
• Read the digital input status of Dupline addresses (status of transmitters)
• Read the values from AnaLink transmitters (analog)
• Read the values from Counter Modules (type G44207401)
• Read the values from Multiplexed Analog Transmitters
• Read the pulse counts on Dupline addresses since last Reset command (note 1)
• Write data to activate digital Dupline addresses (writing a "1" to an address creates the same result as
having an active transmitter on that address).
• Write data to force Dupline addresses ON (writing a "1" to an address will force the receiver outputs with
this address ON, irrespective of the function assigned to that address)
• Write data to be output as multiplexed analog values
• Write data to change the set-points of Analink addresses (can eg be used to change the set-point of a
temperature control function)
• Write data to change switching times on Dupline addresses configured for real-time control
• Issue commands for Reset and Freeze of pulse counts on specific Dupline addresses (Note 1)
Note 1: A pulse counter that increments on OFF-to-ON transitions is automatically assigned to each Dupline
address. The counting is performed on BCD format in the range 0..9999 (if the count exceeds 9999 it will roll-
over to 0). A "freeze" command must be issued prior to reading a pulse count from a Dupline address. The
"frozen" value can then be read while the counting continues in the background. Issuing a reset command for
an address resets the counter for that address.
A Modbus memory map defining which Modbus memory locations are used for the different types of data can
be found in Appendix C of this manual.
The signal status of a given Dupline address can be read in any location related to that address in the Modbus
memory map, but obviously, meaningful data is only achieved from the memory location reflecting the actual
use of that address. If eg an AnaLink temperature sensor is connected to channel B5, it does not make sense
to read the digital status of address B5, but it is possible.
In order to provide easy access to Dupline data from a PC, Carlo Gavazzi offer the Dupline data access
package (DUPDATACC), consisting of a DDE-driver and an ActiveX-server. The DDE-driver offers the
possibility to copy and paste Dupline data directly into EXCEL spreadsheets and other Windows applications,
while the ActiveX driver makes it easy for Visual Basic, C++ and Delphi programmers to access Dupline data.
4.3. COM1
The RS232-port COM1 is typically used for download/upload of Mastergenerator configuration files, because
it has a fixed baud-rate of 115 kBaud just like the configuration software. But it can also be used for
communication with external devices such as PC’s, PLC’s and Touch Screens.
4.4. COM2
The RS232-port COM2 can be used for Dupline-Online operation. When Logged Dupline data is to be
transmitted via Internet to the central Dupline-Online server, COM2 is used to send the Log Records to the
external RS232-to-Ethernet converter ETHCONV1, which then takes care of the Internet transmission. COM2
has an adjustable baudrate in the range 2400 .. 115200 (note: for Dupline-Online operation the baudrate must
be set to 9600). COM2 can also be used for communication with external devices such as PC’s, PLC’s and
