Siemens SIMADYN D Manual page 79

Systemsoftware
Process image
(system mode)
NOTE
Error
differentiation
Communications
Service utility
2-38
Before a task is processed, it is first investigated whether an associated
process image must be updated. If yes, this is realized before the task is
started, by calling-up the system mode of the function blocks (refer to the
Chapter "Significance and use of the process image"). The update is
referred to:
• binary inputs/outputs, for example, the status images for controller
enable signals and the position of limit switches.
• analog inputs/outputs, for example, values for temperature, speed,
etc.
The system mode is started for both tasks to be started before standard
mode processing (refer to the Chapter "Significance and use of the
process image").
SIMATIC TDC/SIMADYN D differentiates between errors, which occur
during initialization and those which occur during standard operation.
Errors from the initialization (INIT operating status) result that the system
is not released for start (transition into the RUN operating status).
For errors in standard operation (RUN status), a differentiation should be
made whether processing is to be continued or terminated.
The system informs the user about its status, especially about the error
statuses, using the 7-segment display on the CPU module.
When an error situation occurs, detailed information is deposited in the
error data fields of the operating system. These error data fields permit a
precise error analysis to be made.
This data can be read-out and changed using the service utility.
The significance of the error signals and information can be taken from
the online help "D7-SYS, Help on events".
Communications handles all of the input/output data transfer between the
hardware as well as the associated software components and the user
interfaces. The interfaces and their parameterization are configured in the
user program using CFC.
The service utility is the central interface of the CPU modules. It is an
instrument for start-up, diagnostics and troubleshooting.
As the processing time of the service utility is undefined, the task
associated with it as well as the tasks with lower priority can be blocked.
This has been implemented, so that service is allocated a maximum
processing time within its cycle (maximum of one basic clock cycle T0).
The service units form the user interface via which the communications
software is controlled.
System- and communication configuring D7-SYS - SIMADYN D
Edition 03.2001