Siemens S7-400 installation manual Error Display, Error Response, Function

Glossary

Error Display

Error display is one of the possible responses of the operating system to a run-time error. The other possible responses include: error response in the user program, STOP mode of the CPU.

Error Handling via OB

When the operating system detects an error (for example, STEP 7 access error), it calls the specific organization block (error OB) for this error, where the further response of the CPU can be specified.

Error Response

Response to a run-time error. The operating system can respond to the following types: transferring of the programmable controller to STOP mode, calling of an organization block where the user can program a response, or displaying of the error.

F

FB

→Function Block

FC

→Function

FORCE

Function which can be used to assign fixed values to specific tags in a user program or CPU (also: I/Os), so that the user program is not able to change or overwrite these values. The function allows users to set defined tag values in the user program for use in specific situations and to test the programmable functions.

Function

According to IEC 61131-3, a function is a code block that does not contains any static data. Temporary tags of functions are stored in the local data stack and will be lost after the FC was executed.

Functions are therefore suitable for storing data in shared DBs. Because FCs are not assigned a memory, you always need to specify their actual parameters. You can not assign initial values to the local data of an FC.

Automation System S7-400	Hardware and Installation	Glossary-5
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