2
Method of operation
gas-net
C1 and C2
Page 2-2
2.1 Host job list (Data exchange module)
The job list of the host describes all data flows to be processed between host
and
gas-net
DSfG Gateway. The system distinguishes between the flow direc-
tion to the host (data export) and the flow direction from the host (data import).
The data transport in the direction to the host is processed cyclically. If a new
value arrives from the DSfG side, the associated export value will be updated. In
addition to the specification of the destination in the host, the description of the
export value also defines the way of positioning the data point in the host (e.g.
size, scaling, limits, bit position).
A particular import value describes for the reverse data flow direction from which
position in the host a data point shall be collected and in which way it shall be
converted. It can be parameterised whether the transmission to the DSfG side
shall be performed cyclically or event-driven.
Any number of import values from the host can be combined to a job group. All
data points of a job group are always put into the transfer memory altogether
and simultaneously, but only after all of them have been collected again once
more. Moreover, a job group may be linked with a trigger. A trigger is a defined
position within the host. It initiates a new processing of a job when its content
has changed.
2.2 DSfG job list (DSfG module)
The DSfG job list describes all data flows to be processed between the DSfG
stations and
gas-net
DSfG Gateway. The system distinguishes between the flow
direction to DSfG stations (export values) and the flow direction from DSfG sta-
tions (import values).
A particular import value for a DSfG station describes the DSfG data element
that shall be collected and put into the transfer memory. For this, any numerical
data element provided by the addressed station can be addressed, without
exception.
Several import values of one and the same DSfG station are combined to a job
group, a so-called
query telegram
. All data elements of a query telegram are
collected via DSfG queries and thus always put into the transfer memory al-
together and simultaneously. DSfG import groups also comply with some spe-
cial features of the DSfG regulations relating to the telegram traffic. For in-
stance, it is possible to process query telegrams either cyclically or upon the
