User`s guide

1-4
1.3 Communications Scenarios
Scenario #1: The DCM-200 initiates a call to the central computer
• The DCM-200 determines that a call should be made due to an alarm condition,
a regularly scheduled call event or a call request from the electric meter.
• The cellular radio within the DCM-200 establishes a connection with the cellular
phone network.
• The DCM-200 initiates an outbound data call (CSD mode) or Internet connection
(GPRS mode) and exchanges meter and status information with the central
computer, which is running Metretek’s DC-2000 data collection software.
• The central computer processes the meter’s data and stores it in a database
structure format.
Scenario #2: The data collection computer initiates a data call to the DCM-200.
• The DCM-200 cellular radio is registered with the cellular network, and is
therefore always ‘listening’ for an incoming call.
• The central computer dials the radio’s “data” number (this is known as a “mobile-
terminate” CSD connection). When the radio answers the call, it will establish a
link with the computer’s modem and will exchange meter and status information
with the computer, which is running Metretek’s DC-2000 data collection software.
• The central computer processes the meter’s data and stores it in a database
structure format.
Scenario #3: The data collection computer “pages” the DCM-200 and waits for the
DCM-200 to call back.
NOTE: In GPRS (Internet) mode it is not possible to contact the DCM-200 via the
Internet because it only acts as a “client” and not a “server” Only a “server” can
accept a request for communications. In CSD mode the cellular service provider
may not support “mobile-terminate” connections. In these cases the DCM can be
“paged”, which will cause the unit to call back immediately.
• The DCM-200 cellular radio is registered with the cellular network, and is
therefore always ‘listening’ for an incoming call or message.
• If the cellular account has been assigned a voice or data phone number, the
computer calls that number. The DCM-200 answers the call, hangs up, and will
immediately call back as described in Scenario #1.