User`s guide

7-1
7 DCM-200’S MODES OF OPERATION
7.1 Overview of DCM-200 Operation
The DCM-200 is a member of the Metretek “SIP” (Survey Instrument Point) family of
data collection devices. By itself the unit can communicate with the data collection
system to report alarm events and other status. It can do this using a CSD link to an
analog modem or with a GPRS connection to an Internet server. The difference
between CSD and GPRS was discussed in Chapter-1.
An ANSI C12-complient meter can be connected to the DCM-200’s RS-232 serial port
using a minimum of three lines; Transmit, Receive and Ground. The DCM-200 is then
configured to match the serial port parameters of the meter such as baud rate, parity,
etc. The electric meter is generally configured to expect an ordinary modem to be
connected to its serial port, and the DCM-200 will respond accordingly. For ANSI meter
applications, only a GPRS connection is supported at this time.
When the meter or the DCM-200 wish to connect to the data collection system the DCM-
200 will register with the cellular network, establish a GPRS data link and then switch to
a transparent state. Data arriving from the system will be passed on to the meter, and
data from the meter is sent to the system. In the background the DCM-200 is monitoring
the status of the cellular link and is accepting and processing commands from the host
system.
The DCM-200 can also accept calls or pages from the data collection system and will
respond in one of several ways. This will be discussed shortly.
7.2 Normal Power-Up / Reset Behavior
Upon power up or manual reset, the DCM-200 will conduct diagnostic tests of its on-
board components. During this time both the green and red LED indicators will light
solidly for several seconds. After completion of these tests, the red LED will turn off and
the green LED should blink at a rate of about once per second.
If the unit needs to be reset manually, two pins on the programming port connector can
be momentarily shorted together, as shown in Figure 7-1.