Hello.Which purpose and function of OB blocks in Step 7 programs?Which is responsible for what?

Thanks.

igor62il

Hello.Which purpose and function of OB blocks in Step 7 programs?Which is responsible for what?

Thanks.

Igor,

OB's are CPU organization blocks: understanding the concept o OB's and mechanism of their execution is crucial for understanding the whole concept of Siemens PLCs.

There are plenty of organization blocks and the main purpose of all of them is to execute user program in the given time intervals or based on different events. So, in short terms, OB's help you to organise your user program based on different criteria.

A brief overview of the most important organization blocks:

OB1: main organization block, is being executed all the time and all over again. It can be interrupted by other organization blocks;

OB30 - OB38: cyclic interrupt organization blocks. They interrupt OB1 at regular time intervals. If you want to execute your user program every 100ms, you put your code in OB35;

OB100: complete restart organization block: is executed once after the complete restart of the CPU. You can use this OB to programm some routine you want to happen only once upon CPU restart, for example to load default plant parameters;

OB40 - hardware interrupt. Lets say you have one digital input and you want to programm some routine when the state changes from 0 to 1: you configure OB40 for this input and put some code that will be executed once every time signal state changes from 0 to 1. Another example can be a counter that is increased every time signal state changes.

OB10: Time-Of-Day interrupt: let's say you want something to happen every day at 10:00 PM: you configure and use OB10 for this purpose.

As a conclusion: OB's are in charge for user program execution, and their existence helps you as a programmer to organize your code in an usefull manner as efficeint as possible.

This is, of course, only a brief overview of Siemens OB concept: there are plenty of useful informations in Siemens Simatic Manager online help. Just mark one OB and press F1.

Hope this helps.

Regards.

igor62il

Hello.Which purpose and function of OB blocks in Step 7 programs?Which is responsible for what?

Thanks.

 Hello,

 attached document  will help you about the purpose of all OBs.

hope help you

regards

hag010

igor62il

this link by france language.I not understand it ,sorry.

 Im sorry , here you are the english doc.

hag010

THANK YOU SO MUCH FOR ENGLISH EDITION.

abhiman saraf