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 op-
erating. The Gateway increments a Node’s missed message count if a Node does not immediately report back from a poll-
ing 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.
Host System
Gateway
Node 1
Node 2
In the sample system shown, the communication link between the Gateway and Node 1 has failed. Node 2 must have its
Gateway Link Failure flag set to allow any outputs linked to Node 1 to be set to the defined default state when the commu-
nication link between Node 1 and the Gateway fails.
SureCross DX80 and Performance DX80 Product Manual
46 www.bannerengineering.com - tel: 763-544-3164 Rev. J
To Next Page
Loading...
