Banner SureCross DX80 Wireless Networks - Manual (Page 45)

5. Double-click Gateway push button 2 to return to the Device Configuration (*DVCFG) menu.
6. Click Gateway push button 1 until reaching the *RUN menu option.
5.8 Default Output Conditions
The timeout structure of the SureCross wireless network sets relevant outputs to user-defined conditions when radio or
host communications fail.
If the timeout features are enabled, the outputs are set to default states or the last known state before the error. The
timeout error conditions are cleared by either a reset command sent from the host, using the front panel display, or using
the auto-recover feature. Communications timeouts occur in three areas within the SureCross wireless system:
• Host Link Failure to the Gateway (Modbus Timeout)
• Gateway Link Failure with any Node
• Node Link Failure with the Gateway
5.8.1 Host Link Failure
A host link failure occurs when the defined timeout period, typically set to four seconds, has elapsed with no
communications between the host system (or Modbus master device) and the Gateway.
The Gateway places an error code in its I/O 8 register and sends a message to all relevant Nodes within the system to set
outputs to the user-defined default states. Each Node has an enable flag for a host link failure condition. If a Node’s ‘host
link failure’ flag is not set, the outputs on the Node are not affected.
In the example shown, a host link failure between the host system and Gateway result in the outputs of Node 1 and Node
2 sent to the defined conditions if both Nodes have the host link failure checkbox selected.
Host System
Gateway
Node 1
Node 2
5.8.2 Gateway Link Failure
Gateway link failures are determined by three global parameters: polling interval, maximum missed message count, and
re-link count.
The polling interval (or rate) defines how often the Gateway communicates with each Node to verify the radio link is
operating. The Gateway increments a Node’s missed message count if a Node does not immediately report back from a
polling request. If a Node’s missed message count exceeds the maximum missed message count, the Gateway
generates a timeout error in the Modbus I/O 8 register of the appropriate Node.
The auto-recover feature uses the re-link count parameter. If enabled, the error condition heals itself if the Gateway and
Node have successfully exchanged N-number of good polling messages. The N-number is the re-link count, or the number
of messages required to re-establish a radio link.
When the Node’s Gateway Link Failure flag is set and the Gateway determines a timeout condition exists for a Node, any
outputs linked from the failing Node are set to the user-defined default state. Each Node has a Gateway Link Failure flag
that can be set or cleared depending on the particular application.
SureCross Wireless I/O Networks
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