NOVUS DigiGate Profibus - Manual (Page 6)

DigiGate Profibus
NOVUS AUTOMATION 6/10
Front lit indicators for communication and status
Tx: Signalizes that the device is sending data through the Modbus RTU network;
Rx: Signalizes that the device is receiving data through the Modbus RTU network;
Status: When permanently lit up, it informs that the device is connected to the Profibus network (normal
operation); when flashing rapidly, it means that there is no connection with the Profibus DP network; when
flashing slowly (once per second, approximately), it means that the device is in “Configuration mode”.
Figure 6 – Front panel of the DigiGate Profibus
Operation principle
This product is designed for transmitting data between two networks with distinct communication protocols. It operates as
slave in a Profibus DP network and simultaneously as master in a Modbus RTU network. The data transfer between both
networks is performed through two tables: the reading table, responsible for making available the data read from the
Modbus network to the Profibus network, and the writing table, responsible for forwarding the data from the Profibus
network to the Modbus network. These tables are configured through the DigiConfig software.
Figure 7 – Operation at the Profibus DP and Modbus RTU buses
Once configured, the product will operate in both networks independently, i.e., it will continuously read the Modbus
network, feeding the reading table, independently from the connection status of the Profibus network. In the same way, it
will proceed communicating with the Profibus master even if there are problems existing in the Modbus network.
At the Modbus side, the device will continue scanning the slaves and reading the desired registers. In case of
communication error, a configurable number of new attempts will be executed. If none of the attempts in a number of
scanning operations (also configurable) is executed successfully, the register block will be considered “disconnected”. In
this case, the communication attempts with this block will be less frequent, i.e., for a configurable number of scanning
operations there will be no communication attempt with this block, and at the following scanning, a new communication
attempt is executed in order to check if the block is now communicating again.
Among the parameters that need to be configured at the Modbus side, we have the baud rate, the parity, the scanning
interval, the number of transmission attempts, the maximum response time, the maximum time between bytes, the
minimum time between commands, the number of attempts before disconnection, scanning factor with disconnected
block. All of these parameters are described in detail in the Help file of the DigiConfig software.
At the Profibus side, it is only necessary to configure the Profibus address of the device. The baud rate of the network
will be automatically detected.