EnCal 3000 page 3
1.2 The EnCal 3000 Controller
The EnCal 3000 Controller is part of the gas quality measuring system. Each controller can process one or two gas
streams, while it is also possible to assign one gas stream to several controllers. This makes it possible, for instance, to
distribute the data of one gas stream to several DSfG buses.
The EnCal 3000 Controller indicates the calibratable measurements superior heating value Hs, standard density rho and
the mole fraction of the gas components in the basic display of the operator panel. The font size of these measurements
is twice as large due to their significance. The EnCal 3000 Controller automatically invokes this basic display again 30
minutes after the last device operation.
The basic display shows the measurements of the first assigned gas stream in dual-stream operation. You can switch to
the corresponding display of the second assigned stream with a menu command.
The EnCal 3000 Controller is also equipped with a data logging function that logs important measurement variables. A
Long-term archive is available as a certifiable archive type, which logs the calibratable measurement variables cyclically
every 15 minutes. There is one separate certifiable Long-term archive available for each gas stream.
The data logging function logs the measurements provided by the gas chromatograph. It is also able to log further
measurement variables provided by operational supplementary functions. The measurement variables to be logged are
provided with a time mark of the data logging time and a classification criterion, the ordinal number. They are saved in a
storage area that is organized as ring storage. If the ring storage is full, each new data record overwrites the oldest one.
If the controller is the one taking on the active function within the Modbus communication with the gas chromatograph, it
can also be used to perform manual calibrations or test gas runs.
In addition to the displaying and data logging function the EnCal 3000 Controller offers a variety of operational
supplementary functions; for instance, for monitoring tasks and data communications. The certifiable functions are
isolated from each other and from the operational functions.
The controller monitors itself and all incoming measurements. If it detects an internal error or an error in the
communication with the gas chromatograph and if this error affects the accuracy of the measurement variables, this error
will be indicated by a red flashing status LED and additional clear text. During such an error the last two measurements
measured before the error will be maintained. After the error has been eliminated, the EnCal 3000 Controller switches
automatically back to the current online values.
The EnCal 3000 Controller is equipped with up to two digital data interfaces of the DSfG type (DSfG stands for Digital
Interface for Gas Metering Device), which is used by all devices in the Elster gas-net device family as described below.
The controller uses the interface labeled DSfG to provide other measuring instruments connected to the DSfG multidrop
connection and typically calibrated (e.g. flow computers) with the calibrated target variables Hs, rho and the entire
analysis.
For this, the EnCal 3000 Controller operates exactly according to the method specified by the DSfG regulations. If new
measurements are available, the EnCal 3000 Controller sends a New measurements attention telegram. Data sinks
being interested in the values due to this signal have to get hold of these values by themselves by means of query
telegrams. In the EnCal 3000 Controller the transferred calibrated data is provided with an additional signature, which is
checked for integrity in the receiver. This procedure ensures the accuracy of the transferred data.
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