WI-MOD-E-100 & WI-MOD-E-300 Wireless Ethernet
User Manual
WI-MOD-E Manual v1.10
Page
60
Modes of operation
As mentioned earlier, there are 3 modes of operation that the WI-MOD-E can use to route data
between the connected devices:
•
Protocol Aware Routing
. If the WI-MOD-E is aware of the protocol used by the remote
devices then it can efficiently route data only to the required location based on the
addressing inherent in that protocol. The WI-MOD-E currently supports the ModBus RTU
protocol. When this mode is used, the WI-MOD-E initially has to learn the location of slave
devices by broadcasting requests to unknown slave devices. However, once the slave device
responds its location is learnt, and an entry is made in the internal routing table so that
subsequent data directed at that slave device is sent only on the desired remote device
connection.
•
Master/Slave Routing
. If the protocol used by the remote devices is a Master/Slave type
protocol (i.e. a single master device requests data transfers with slave devices), but is a
protocol other than ModBus RTU, then data being sent by the master device is broadcast to
all connected slave devices since the router can not know the required destination without
knowledge of the protocol. However, data being sent by any slave device is always routed
only to the master device.
•
Broadcast Mode
. If the protocol being used by the remote devices is not a master/slave type
protocol – then data being sent by any remote device can be broadcast to all other connected
remote devices. This is the least efficient mode in terms of data transfer, however may be
suitable for point-to-point or small multipoint systems, or in cases where the amount of data
being transferred is small.
Settings
The WI-MOD-E can route data between up to 10 separate groups of remote devices using any of the
3 modes described above for any group. These
Routing Servers
can be configured on the Network
Settings configuration web page. The current module firmware can support a maximum of 50
remote devices connected to the WI-MOD-E in total. If at least one master and one slave device are
connected to a Routing Server in Master/Slave mode – or at least two devices are connected to a
Routing Server in broadcast mode, the Link LED will be illuminated; otherwise the link LED will
be off. The link status for each Routing Server is also available in onboard ModBus status registers
(see ModBus I/O Transfer section), and comprehensive connection statistics are available online via
the Statistics configuration web page
TCP/IP Configuration
Keepidle
This is the time (in seconds) before the first keep-alive probe is sent
on a given TCP/IP connection (if keep-alive probes are enabled for
that connection).
Keepintvl
This sets the interval in seconds between keep-alive probes on a
given TCP/IP connection. If eight successive keep-alive probes are
sent with no response, then the connection is dropped.