You can always create a loop and loop through all possible addresses you might use, capture the errors if any so you don't halt the PLC, and note which addresses are valid so you can subsequently just scan the I/O that really exists.

On the other hand, the real question should be, why would you want to use the old s7-300 programming when you have an s7-1200?  Build it right in the s7-1200 and you may find you save a lot of effort in the long run trying to squeeze 100 kg of stuff into a thimble and expecting it all to fit just like it did in the big sack of stuff you had before. 

mbes

Hello,

I'm trying to adapt my 300 code for 1200 PLC for reading from a peripheral address:

 #byte1 := BYTE_TO_DWORD(%IB(#InterfaceParam1 + 1):P);

 and I have a problem to do that.

If I'm not wrong, for fixed address (as e.g. %IB7) I could just type it in a following form:

 #byte1 := BYTE_TO_DWORD(%IB7:P);

for which a tag would be created and line turned automatically into:

#byte1 := BYTE_TO_DWORD("Tag_1":P);

(BTW. any suggestion how to disable this automatic tag "placement"?).

Can I do anything similar for "calculated" address (as #InterfaceParam1 + 1), possibly directly, without using a tag and reassigning it's value?

 On the other hand, I could (should) use the PEEK function:

#byte1 := BYTE_TO_DWORD(PEEK(area := 16#1, dbNumber := 0, byteOffset := #InterfaceParam1 + 1));

but accorrding to the TIA manual, peripheral inputs are supported only in 1500:

TIA help

16#1: Peripheral input (S7-1500 only)

 Do you know any solution that could help?

Thanks

Marcin

Peek if you are unable to know in advance what address you are reading.

ab#:P if you know in advance what you are reading - where a = {I, Q} and b = {"", B, W, DW} and # is the address.

You should only read the periphery if your project needs it.

And, you should not convert an s7-300 project to s7-1200.  You should look at it from a different perspective and find out how you _should_ write it using symbolic addressing where possible and appropriate.

If you are unable to write it using symbolic addressing, you are losing a lot of the power of portal and s7-1x00's.

If I still have not answered your question and given you advice you are probably going to ignore for a few years, you are of course free to comment.

mbes

Thanks for your answer, but this is not really providing anything new. It's not a new functionality, that I'm asking for, right?

So, maybe I can sum up my question in one sentence:

Is there a way to read from given peripheral address using 1200 in TIA?

If no, is there any good explanation why shouldn't I ask for it?

Thank you.

mbes

Hi there,

I think what you ask is not possible for the S7-1200
A work-around would be to use a CASE function
if the address you look for is limited.

Seeing that I am a mere user and
do not work for Siemens, you can expect some error.
Please feel welcome to ask Siemens Support directly:
https://support.industry.siemens.com/my/ww/en/requests#requests

Good luck.
w

Indirect :P is not possible in 1200's as you found out.

CASE in SCL would be very useful if you provided an exhaustive list (and captured all errors within the block).

For example, if you assign all I/O consecutively, you can loop through the periphery addresses with a single loop / case statement.

That said, I would hope your project only needs to read a few :P addresses.

All that said, given the limitations of the I/O count of the s7-1200s where :P might really be necessary, you could just do this:

Write out in SCL all the :P addresses  you can imagine needing in all projects using this shared code.

Comment out what you do not need for each project.

Since you can export and import SCL with relative ease, you could automate this task with a piece of software that adds and removes comments to the appropriate I/O and now your project is doing what you want with code you only write once.

mbes

Thanks for the advice and please, do not have an impression I do not appreciate it. The fact that I "adapt" old code doesn't necessarily mean I just try to make it work on 1200 in TIA.

Anyway, my project needs access to periphery and that's why I asked this question. Both of your suggestions seem reasonable and I've suggested them in the first place, but:

1. using Peek function - according to the help, only 1500 supports the area of peripheral inputs (16#1)

2. I cannot use "old" notation (ab#:P) as I compute my address based on variable, and that's what you meant?

If that's correct, does it mean that user can not read from indirect peripheral address?

Thanks,

mbes

mbes

Academical thought..

I assume that the coding is needed for making it possible for the user to identify a custom input pin that can be read by an interrupt as immediate signal.

When employing any type of indirect addressing there is a CPU processing penalty to be paid. This may negatively influence the interrupt code.. especially for the S7-1200. Even the use of CASE function for lets say 8 or so bytes may have some tax to pay.

Also... the inputs onboard to the PLC has the best reaction time. When working with those, you could expect 3 bytes at the most to choose from: IB0, IB1 (CPU1214++) and IB2 (add on signal board) (address assumed defined as stated). That would better the working for the CASE function..

CASE #selection OF
0:
       #myByte := IB0:P;
1:
       #myByte := IB1:P;
2:
       #myByte := IB2:P;
END_CASE;