Mapping/Data Blocks

Hi guys,

I am new to this forum and just started out programming Siemens PLCs and do have a couple of questions:

1. First of all do all Siemens PLC scan I/O synchronously?
2. Is I/O mapping necessary like it is with other PLC brands or just to keep the program clean?
3. Do you guys use Data Blocks to setup some kind of Input Mapping? Or Output Mapping? Because I definitely saw some examples online where a (PLC) Data Block ,named HMI communication, has been created to connect to the HMI.
4. What is a good way to get organized from the start in Step 7 (using V16)

Any advice, links to advice etc are appreciated! Any screenshots of how of you set your Program Block Tab up would be even better.

Thanks and Regards

Julian

Mapping is definitely not necessary with the dynamic optimization in TIA you can directly make any changes in IO or even in the DB Variables and the same will be applied throughout the project 

Data blocks (DB) are used for storing variables of different data types, For single/multi instance memory of the Standard block call.

For programming guidance there are many manuals, Documents, Example Projects and videos are available in the SIOS portal

you can access from below link

https://support.industry.siemens.com/cs/ng/en/view/109751825

https://support.industry.siemens.com/cs/ng/en/view/65601780

Julian1892

...

1. First of all do all Siemens PLC scan I/O synchronously?

...
3. Do you guys use Data Blocks to setup some kind of Input Mapping? Or Output Mapping? Because I definitely saw some examples online where a (PLC) Data Block ,named HMI communication, has been created to connect to the HMI.

...

Hello Julian.

I will be brief as today is not the day to ask for specifics. May these notes focus your attention to some areas of learning when studying the PLC manuals.

NOTE: The PLC you use is important. There are two ranges: classic and current versions. Some workings differ between the ranges. Best to be specific. Also say which Step7 version you use (you did say V16 this time).

(1) By default the local IO is scanned in sync with the PLC cycle (OB1) if the IO address is within a designated range. This can be changed by modifying the hardware configuration. Manual updating or per time / event updating is possible. Direct reading/writing of the IO is possible, which is helpful when dealing with interrupts.

Remote IO is handled differently. Updating those are done on timing as configured in the hardware configuration.

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(3) IO mapping makes most sense where repeated structures are needed. Think of networked drives for example. The current PLC range can however structure IO symbols into a structure (UDT) without the need to access a DB first.

IO mapping is of value where time updated IO needs to be forced into scan cycle update.

Some older PLCs made it difficult to rewire IO functionality to another IO pin. Working with symbols, such a change is as easy as reassigning the symbol to another IO pin.

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Regards.

qwazee

(1) By default the local IO is scanned in sync with the PLC cycle (OB1) if the IO address is within a designated range. 

If that was true there was no need for a synchronous cycle interrupt.