Echelon SLTA-10 - SLTA-10 Adapter Connection States

SLTA-10 Adapter User’s Guide 97
In NSI mode, the SLTA-10 Adapter can be configured to initiate the connection with the host PC
when LNS network management messages and/or network variable updates are addressed to the
SLTA-10 Adapter. Alternatively, another node on the local network can command the SLTA-10
Adapter to initiate the connection.
In MIP mode, the SLTA-10 Adapter cannot itself initiate any connection; it must be commanded to
do so by another node on the local network, or else by the modem's detection of an incoming call.
This means, for example, another node on the local network must initiate the dialing procedure
when an alarm is detected that needs to be reported to the host. Once a connection has been
established, however, any node on the local network can communicate with the host by addressing
messages to the SLTA-10 Adapter.
In order to support the modem functions, the SLTA-10 Adapter Switch2/CFG2 input must be set to
the
Remote Host
state (UP position). Switch1/CFG3 should be set to the default ALERT/ACK link
protocol (DOWN position). This automatically enables the reliable network interface transport
protocol. See Chapter 4 for details of the configuration inputs. See Chapter 7 for using the
SLTALink Manager with the SLTA-10 NSI mode or Chapter 8 for SLTA-10 MIP mode DOS
network driver options.
Note that the packet throughput of the SLTA-10 Adapter is substantially reduced when using a
modem because of the overhead associated with modem support.
SLTA-10 Adapter Connection States
When the SLTA-10 Adapter is operating in the remote host mode, several internal states (or
connection states
) will control its behavior:
•The
IDLE
state is entered after power-up reset. In this state any uplink bound messages are
ignored since the SLTA-10 Adapter is not connected to a host. The
IDLE
state is also entered
whenever the telephone connection is broken and the modem drops the DCD (Data Carrier
Detect) line.
•The
CALL_IN_PROCESS
state is entered once a connection is initiated by a node on the
network connected to the SLTA-10 Adapter. In this state uplink traffic is still discarded while
the SLTA-10 Adapter monitors the modem for connection completion or connection failed
events to occur.
•The
CONNECTED
state is entered once the connection is complete. The normal network
interface protocol resumes between the SLTA-10 Adapter and the remote host. This state may
be entered as a result of a node on the local network initiating a call, or as a result of a remote
host calling up this SLTA-10 Adapter.
•The
FAILED
state is entered if the connection process failed. This state is operationally the
same as
IDLE
.
The connection state of the SLTA-10 Adapter is preserved across software resets, allowing normal
network management resets to occur without breaking the connection. The SLTA-10 Adapter will
not preserve the connection state after it has been through a power reset.