Instructions

UM-0085-B09 DT80 Range User Manual Page 222
RG
• DDNS update aborted. Modem interface is on private LAN – DDNS will only work if the DT80
has a public
IP address. If it has a private IP address (10.x.x.x, 192.168.x.x or 172.16-31.x.x) then there is no
point giving this to a DDNS server because no system outside the private network will be able to reach it.
Communications Sessions
DT80 integrated modem models are often deployed in remote locations, with limited power available. Power
management is therefore very important in these applications.
To minimise overall power usage, the DT80 allows modem communications to be grouped into communications
sessions. During a session, the DT80 will automatically:
• switch on the modem and connect to the mobile network
• send any alarm SMS messages
• perform any data transfers (alarm messages or data unloads)
• manage retries in the event of a communications failure
• optionally remain online for a period of time to allow you to connect to the logger using dEX or DeTransfer
• switch off the modem
A number of settings are available to allow you to trade off power consumption against:
• accessibility – you can only connect to and remotely control the logger while the modem is switched on, and
• notification delay – you can specify whether to immediately establish a connection following an alarm event, or
whether it can wait until the next scheduled session
Note: A similar "communications session" mechanism is also used for Ethernet transfers, although without any of the power control
features. For more details see
Ethernet Sessions (P229). The remainder of this section will deal with modem communications
sessions, and is therefore applicable to DT8xM models only.
Session Timing
Starting and Ending a Session
The DT80 will begin a communications session when any of the following events occur:
• an SMS or email alarm action is triggered, unless the action is designated "low priority". (Low priority alarms are
queued and will be sent when a communications session is next started for some other reason.)
• an email or FTP data unload is triggered, unless the unload is designated "low priority"
• the current time falls within the defined session time window, if any.
• the SESSION START command is issued, or the Start comms option is selected on the keypad function
menu
• a session retry is required following an earlier communications failure
The session will then continue until any one of the following occurs:
• the configured maximum session duration is exceeded (by default there is no maximum), and the current time is
not within the defined time window
• the configured minimum session duration has elapsed, and communications have been idle for the configured
minimum idle time, and the current time is not within the defined time window. By default there is no minimum
session duration and the minimum idle time is 2 minutes.
• the SESSION STOP command is issued, or the Stop comms option is selected on the keypad function menu.
• a communications failure occurs
Priorities
Alarms and data unloads may be designated as either "normal priority" (which is the default) or "low priority". When a
normal priority alarm or unload file is generated, a communications session will immediately be started, if one is not
already active. A low priority alarm/unload, on the other hand, will not automatically start a session.
If no session is currently active then a low priority alarm/unload will be queued until either:
• a session is started for some other reason, e.g a normal priority alarm/unload occurs, or the
SESSION START
command is issued, or
• a queue has no more space available, or
• 24 hours elapses since the low priority item was generated