GE Industrial Solutions 6KCV301DGF - Manual (Page 17)

17 —————— Digital General Function Card ——————
6KCV301DGF
CPM Mathematical co-processor 387.
DPRAM DPRAM is a bi-accessible storage device that allows the DGF
to communicate with the connected drive. Various connection
structures are available, with different exchange capacity and
priority.
I/O OPTIONAL CARD It is possible to add additional cards to expand the
hardware capability of the DGF. The detailed description of
these devices can be found in their specific documentation.
The DGF can be provided with various I/O cards.
DBASE DBASE is a block used for the communication with the external
world. It is a catalog of variables provided by the DGF and
containing different information on the system. For each
variable access modes are specified, for example:
- read-only or read and write
- limits of the variable value
- access level, etc.
All information coming from or directed to the external world
goes through DBASE.
ARCHIVE Archive is a particular storage area where DBASE data are
stored so that the DGF can restart after a supply voltage failure.
2.1.2 Working of the DGF
The software of the card is based on the multi-task real-time operating system called
MARTE.
The structure of the program comprises a nucleus of 5 tasks with the following
characteristics (see Figure 2.1.3.1):
TASK SYN DPRAM This task executes the communications with the drive, for the
parameters at high priority , using the SYN DPRAM structure
of the DPRAM. The connection is executed with the maximum
priority at constant frequency. The event which wakes up the
task is a signal coming from the drive, whose execution is
synchronous with the regulation task of the drive.
TASK PERIOD This task carries out the regulation program developed by the
user. The task is normally carried out as a sub-routine of the
task SYN DPRAM. As a consequence, it inherits the main
characteristics:
- execution at the maximum priority ,
- constant priority
- synchronous with the drive.
In particular applications the task could be carried out in an independent way from the
task SYN DPRAM. In this case the execution of the task is carried out in an
asynchronous, with respect to the drive.