User`s guide

iii
COMMON QUESTIONS
What does this device do?
Electric utility meters have historically required a person to visit each site and manually record the
readings on a regular basis. Modern meters now contain processors, memory and phone line
modems that eliminate the need for on-site visits. With this method much more information is
available and can be gathered in a timelier manner. With this evolution came a need to develop a
universal way to communicate with any of these meters, regardless of the manufacturer. A
standard was developed by the Accredited Standards Committee on Electricity Metering, C12,
and was approved by the American National Standards Institute, or ANSI. Any meter following
this standard is expected to behave and communicate in a consistent manner.
Yet there are some problems associated with wired telephone service. There may be no lines
available in the area where the meter is installed. In some cases it may be physically impractical
or too expensive to run a phone line. The communications speeds offered by the internal
modems are relatively slow, resulting in long communications sessions. Finally the monthly
charges for phone service may outweigh the advantages of an automated system.
Metretek’s DCM-200 is a wireless system designed to connect to an ANSI C12-complient meter
and transfer its information over common digital cellular phone networks. The unit supports 850 /
900 / 1800 / 1900 MHz GSM, the primary cellular system used throughout most of the world.
Depending upon the cellular service provider’s capabilities, the DCM-200 can originate calls,
receive calls or both. The DCM-200 can communicate with another modem using a circuit-
switched data (CSD) connection, or can use the general packet radio standard (GPRS) to
exchange information over the Internet.
See Chapter-1 for more information.
Does the DCM-200 use a cell phone?
The cellular radio module is similar to that used in a digital cellular phone, but there is no display,
keypad, speaker or microphone. Instead it has a communications port that allows the DCM-200’s
processor to control the radio and use it as a wireless modem. Also, the radio is designed for
more severe environmental conditions than a commercial cell phone.
There are references within this document to “mobile” devices because the cellular radio system
was intended to support portable phones and equipment. Though the DCM-200 is normally
installed in a fixed location, it is still classified as a “mobile” device.
Does it matter where the DCM-200 is installed?
Yes. The DCM-200 is designed for indoor or outdoor use and therefore can withstand wide
variations in temperature and humidity. But the radio signals are affected by metal buildings, by
the distance from the cell tower and interference from nearby electrical equipment. Chapter-2
has much more information.
Also, and this is very important, the DCM-200 must not be installed in any area classified as
“hazardous”.