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gACC-499E/U Communication unit
gACC-499E_U_Manual_EN.doc
1.
Introduction
1.1
General
The gACC-499E/U is specially developed for the so-called SME segment where the used gas meters or
gAVC 1200 can be read remotely to retrieve the actual meter readings. Essential is the use of optical
encoders with a NAMUR communication output. As a result, it is possible to perform a cyclic read-out of the
index value by using the IEC62056-21 protocol. Other communication methods are available on request. The
gACC-499E/U is available in mains power supply and battery power supply. The mains power supply version
can be used for short measuring cycles and frequently used communication, e.g. for feeding a web portal.
The battery power supply version is suitable for daily, weekly or monthly communication modes. In daily
communication, with good network coverage, the battery life span (2pack) will be approx. 6 years.
1.2
Basic construction
The modem gACC-499E/U consist of 2 main compartments whereby the largest compartment is equipped
with a mainboard on which the power supply terminals, inputs and the TC-65i or TC-65ix module carrier are
placed. The smaller compartment contains a multi-channel Zener barrier which complies with the ATEX
directive 94/9/EC for all possible input signals. The compartments are separated by a removable dividing
wall.
The Zener barrier EX-499-UW complies with an associated intrinsically safe apparatus in the form of a max.
5-channel Zener barrier. The number of channels depends on the application.
Normally the device is supplied completely configured, whereby the SIM card can be placed if requested by
the customer. The connection of the unsafe side is at the top of the Zener barrier performed by a plug
connection. The intrinsically safe outputs and terminals for the potential equalizing are located at the bottom,
so in the standard version in the terminal compartment of the housing.
The gACC-499E/U can be used for several applications whereby it can operate as a stand-alone data logger
for e.g. index readings of a gas meter with a NAMUR encoder, a simple pulse generator or as
communication unit for the gAVC 1200. For every application a specific configuration file is necessary. By
using an 8-pole DIP switch the device can be set to the desired application. Time windows can be applied to
let the gACC-499E/U login to the net at fixed intervals. After that there can be dialed-in by using a data
collection system. These settings are stored in a XML-file in the memory of the gACC-499E/U.
By using the gACC-499E/U in combination with an gAVC 1200 there will be a protocol conversion from
MODBUS RTU to IEC62056-21 performed. The specific settings of the gAVC 1200 can be performed in a
transparent mode via the gACC-499E/U. The configuration program of the gAVC 1200 can make a
transparent connection by using a modem, whereby all the parameters can be read. With the availability of
metrological rights all parameters can also be programmed.
The gACC-499 E/U can communicate data via the IEC62056-21 protocol where 3 main functions are
supported.
1. Billing data,
2. Load profile data
3 Time synchronization.
For this protocol is a separate detailed protocol description available (gAVC_1200_IEC62056-21.pdf). In
addition an access password (P1) can be used to prevent unwanted connections with measurement.
GA-02.035-EN-30.05.17
Page 4 of 46
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