Specifications

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• Network reply timeout (ms)
If the "Request-reply communication" is set to "yes", the time of waiting the answer
from IP device
• Max packet from serial (bytes)
The max. amount of bytes received from serial device, after which the packet is sent
• Max packet from network (bytes)
The max. amount of bytes received from the IP device, after which the packet is sent
• Serial frame spacing (ms)
The time of a pause in serial traffic, after which the already received data is sent
• Network frame spacing (ms)
The time of a pause in IP traffic, after which the already received data is sent
15.2. Serial GW modes
The Arctic Gateway products have two modes of operation, while converting the serial traffic for
TCP/IP connection.
• Server
Arctic will wait TCP/UDP connections coming to its serial GW (TCP/IP) local port.
Once the SCADA server establishes the connection, Arctic is able to send the events,
as they come from serial line, via TCP/IP to SCADA server without polling. Server
mode is typically used.
• Client
Arctic will connect to an IP address and TCP/UDP port of a server in order to send the
serial events over TCP/IP.
15.3. Serial ports
The Arctic, depending on the model, supports one RS-232 serial port only for console connection
or two serial ports, one RS-232 switchable between console and application and one port
switchable between RS-232 and RS-422/485. The RS-485 and RS-422 ports are using differential
(balanced) signaling providing good noise immunity.
15.4. Cabling
Arctic is a DTE (data terminal equipment) device as computers in general are. Serial devices, like
e.g. modems are DCE (data communications equipment) devices.
In practice, this means that if you connect the Arctic to a computer, a cross-connected cable is to
be used. If the Arctic is connected to a serial device other than computer, check the serial device’s
documentation of whether it acts like DCE or DTE equipment.
15.5. RS-485 characteristics
• Also known as RS-485 Half Duplex, RS-485 2-wire
• Same pair is used to transmit and receive data
• Only one device can transmit on the bus simultaneously because the bus is shared
15.6. RS-422 characteristics
• Also known as RS-485 Full Duplex, RS-485 4-wire
• Separate pairs for transmit and reception