Specifications

Niagara Release 2.3
Revised: May 22, 2002 Niagara Networking & Connectivity Guide
Chapter 4 Connecting with Direct Dial
Niagara Considerations
4–4
station will always dial-up the JACE-NP (or JACE-4/5s), but it will never be dialed
into. This is not a function of the machine, or its dial configuration, but rather is a
function of the information that it sends or receives.
In the examples above, two JACE-4/5s are shown dialing into one Web Supervisor,
however, only one of them is connected at any one time. When one JACE is
connected to the dial-in host (in this case, the WS), and the second JACE attempts to
dial in, the second JACE continues to retry the dial-out until it is successful. After
several failed connection attempts, the “wait between dials” time will increase to a
maximum of 2 minutes. As soon as a connection is made, the wait time for the JACE
is reset back to just a few seconds.
User- versus Application-initiated Connections
You can also think of the connections between direct-dial hosts as user-initiated or
application-initiated. Application-initiated connections are Niagara station-to-station
connections. Examples include:
• a station on a JACE dialing a Web Supervisor station to deliver log archives or
alarms.
• a station on a Web Supervisor dialing a JACE station to deliver an alarm
acknowledgement.
Examples of user-initiated connections include:
• a user on the Web Supervisor or remote engineering host using the JDE to
engineer a job on a remote JACE.
• a user on an engineering host using the Admin Tool to manage a host (start,
stop, change settings, etc.).
These concepts are illustrated in Figure 4-3.
Figure 4-3 User- and application-initiated connections between direct-dial stations.
JDE
Web
Supervisor
station
Admin Tool
Alarm
Console
JACE
station
User-initiated
connections
Application-
initiated
connections
1. Engineer station
2. Manage host
3. Report alarm
4. Archive log
5. Acknowledge alarm*
6. Get polled archive
5. Acknowledge
alarm*
* The operator acknowledges the alarm with the Alarm Console, then the Web Supervisor station
sends the acknowledgement to the JACE station, making it an application-initiated connection.