Specifications

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When configuring the IEC-104 for GPRS connection, one can start with the following values:
• IEC t0 (connection establishment timeout, SCADA only) > 30 secs
• IEC t1 (ack rx timeout) = 60 secs
• IEC t2 (ack tx timeout) = 20 secs
• IEC t3 (link test interval) = 200…600 secs,
SCADA should have approx. 30sec less than arctic
• IEC k (tx window size) = 12
• IEC w (rx window size) = 8
• Any completion/control/GI timeout > 60 secs
See Arctic IEC-104 Gateway’s User’s manual for more settings.
20.2. Arctic Modbus Gateway
The Arctic Modbus Gateway offers the following key properties:
• Supports Modbus RTU and Modbus ASCII serial protocols
• Supports ModbusTCP, ModbusRTU over TCP, ModbusRTU over UDP, Modbus
ASCII over TCP and Modbus ASCII over UDP network protocols
• Can generate and filter out gateway exceptions
• Can route traffic on network based on Modbus addressing enabling intelligent use of
network resources
• Makes automatic connection management
• Enables multiple server sessions over network
• Offers unlimited amount of Masters on serial or Network side
• Offers 30 routes over network to slaves.
See the Arctic Modbus Gateway specific settings from Arctic Modbus Gateway, Configuration
Manual.
21. Appendix E: Troubleshooting
Troubleshooting the solution may sometimes be a difficult task. It is a good practice to divide the
solution into smaller subparts, e.g. LAN and WAN connectivity, VPN tunneling, routing, serial
connection and so on.
21.1. Troubleshooting principles
• Define the environment
– how it should work?
Technologies, products, protocols, network design
• Gather the symptoms
– how you see the problem?
What is not working, where you can see it?
• Isolate the root cause
– analyze, rule out
Follow good troubleshooting practices
• Create a solution
– focus for permanent solution
Permanent solution rather than a quick fix