Some questions about Allen Bradley PLC

[mohssen 0]

Dear Professionals,

I am new in AB PLC, but I know Siemens PLCs. I must learn AB and I appreciate any help regarding below basic questions:

1) What is the OS (Firmware) in AB PLC? Is there any OS commands concerning AB programming?

2)How does AB PLC execute the program in the cpu? ( in Siemens PLC, there are OB( organization Blocks) to write logic program and OB1 executes cyclically and therefore, any block which  is called in OB1 is executed by the cpu cyclically as well. Can we compare it to AB?)

3)How is the structure inside AB CPU concerning the RAM (different areas in the RAM for user program and OS etc), Micro-Processor, Memory Card etc

4)How AB PLC reads/writes IOs from the I/O modules? is there any Image area in the RAM for digital IOs ? how about analog IOs?

As I am very new in AB programming, some of above questions may look silly, but any guide is highly appreciated. I need to start from somewhere :)

Thanks 

 

 

[Michael Lloyd 85]

Quote

1) What is the OS (Firmware) in AB PLC? Is there any OS commands concerning AB programming?

2)How does AB PLC execute the program in the cpu? ( in Siemens PLC, there are OB( organization Blocks) to write logic program and OB1 executes cyclically and therefore, any block which  is called in OB1 is executed by the cpu cyclically as well. Can we compare it to AB?)

3)How is the structure inside AB CPU concerning the RAM (different areas in the RAM for user program and OS etc), Micro-Processor, Memory Card etc

4)How AB PLC reads/writes IOs from the I/O modules? is there any Image area in the RAM for digital IOs ? how about analog IOs?

I programmed S7-200, 300, and 400 CPU's before I started using the CLX. Personally, after years of programming Siemens S7's, while I still like them, I prefer the AB CLX line. For me it's faster and more streamlined. 

1) I'm not sure what you are looking for here? 

2) AB has Tasks. The Main Task is a continuous task. Inside the Main Task there is a MainRoutine. Inside the MainRoutine you place logic and calls to subroutines. Subroutines can be written in ladder, structured text, function block, or Sequential Function Chart. You can also create a Periodic Task and set the rate of execution or an Event task that runs when a specified event occurs. 

3) I don't concern myself with RAM other than making sure that there is enough. The OS manages that. 

4) No offense intended but these questions sound more like a hacker than a programmer. None of this is important for writing a program. None of it.