Siemens ET 7Y Series Especificaciones descargar pdf (Pagina 153)

Functions of the IM 151-7 CPU

8-41

ET 200S IM 151-7 CPU Interface Module

A5E00058783-04

8.10 Data consistency

A data area is said to be consistent if it can be read/written by the operating

system as a single block. The data that is transmitted together between devices

should stem from one processing cycle and thus should form a unit, i.e. be

consistent.

If there is a programmed communication function in the user program, for example

X-SEND/ X-RCV, that accesses shared data, the access to this data area itself can

be coordinated using the “BUSY“ parameter.

For PUT/GET functions

For S7 communication functions, such as PUT/GET and read/write via OP

communication, that do not require a block in the user program of the CPU (as

server), the size of the data consistency must be taken into account during

programming.

The PUT/GET functions of the S7 communication or reading/writing of variables

via the OP communication are processed in the cycle checking point of the CPU.

To ensure a defined process alarm reaction time, the communication variables are

consistently copied in blocks of a maximum of 64 bytes in the cycle checkpoint of

the operating system into and out of the user memory or memories. Data

consistency is not guaranteed for any large data areas.

If a defined data consistency is required, the communication variables in the user

program of the CPU may not exceed 64 bytes in size.

1 2 ... 148 149 150 151 152 153 154 155 156 157 158 ... 213 214

Sin comentarios

Siemens ET 7Y Series Especificaciones Pagina 153