DP CP coupler data transfer and communication

Hello Oluwasedago;

A  variable of datatype REAL occupies 4 bytes (32 bits) and is formatted based on IEEE 754: look in the S7 online help or

https://en.wikipedia.org/wiki/Single-precision_floating-point_format

So your S7 address should be QDxxx, the D indicating a 4 byte value, or IDxxx, or DByy.DBDxxx. And you must format that address as a REAL (right click on the I or Q address to open the symbol table, mark it as REAL).

Try it...

Hope this helps,

Daniel Chartier

 Hello Daniel,

Thank you very much!

Now, I can view the real data as well as the Boolean data.

I think I will delete the "Consistent" input and output configs and work only with the Non consistent ones, since I have a working platform now and do not really know how that would work on the Beckhoff side and do not know how to make them work on the Siemens side.

I will probably just increase the Inout and Output bytes to be able to get more bytes for the real values transfer. I am very grateful for your time and help.

Regards,

David

dchartier

Hello Oluwasedago;

A  variable of datatype REAL occupies 4 bytes (32 bits) and is formatted based on IEEE 754: look in the S7 online help or

https://en.wikipedia.org/wiki/Single-precision_floating-point_format

So your S7 address should be QDxxx, the D indicating a 4 byte value, or IDxxx, or DByy.DBDxxx. And you must format that address as a REAL (right click on the I or Q address to open the symbol table, mark it as REAL).

Try it...

Hope this helps,

Daniel Chartier

TIA V16 update 4, S71500 and Beckhoff Twincat 2.9

Hello, Please I have gone ahead to set up communication on the Beckhoff part and so far all hardware communication setup is perfectly fine.

We have decided to use 2 X 64Bytes Inputs and outputs and 1 Byte Input and Output for Communication Check.
That is:

1 Byte Output_1: Communication Output Checks from Siemens (Address 10)

1 Byte Input_1: Communication Input check from Beckhoff (Address 13)

We access bits from these and so far all is fine.

For the Data Area, we plan to transfer various data in sections over:

64 Bytes Input_1: Data From Beckhoff_1 (Address 20..83)

64 Bytes Input_2: Data From Beckhoff_2 (Address 84..147)

Here, we have sent some data from the beckhoff, but I cannot access it directly on the Siemens.

Even when I check the direct address of IB, ID or IW, I get some strange data. I know the data is thee, but I do not know how to address to access it. I noticed while setting up my DB that the REAL data type tries to take 5 bytes instead of 4 bytes. When I drag the columns from ID20, the next one shows as ID25. I manually constructed the DB to have 4 bytes spacing.

Please, could you help inform me of how to get these data with the right addressing?

I have attached the set up and the data view from the beckhoff and also what I see in the Watch Table on TIA.

oluwasedago

 Hello Daniel,

Thank you very much!

Now, I can view the real data as well as the Boolean data.

I think I will delete the "Consistent" input and output configs and work only with the Non consistent ones, since I have a working platform now and do not really know how that would work on the Beckhoff side and do not know how to make them work on the Siemens side.

I will probably just increase the Inout and Output bytes to be able to get more bytes for the real values transfer. I am very grateful for your time and help.

Regards,

David

dchartier

Hello Oluwasedago;

A  variable of datatype REAL occupies 4 bytes (32 bits) and is formatted based on IEEE 754: look in the S7 online help or

https://en.wikipedia.org/wiki/Single-precision_floating-point_format

So your S7 address should be QDxxx, the D indicating a 4 byte value, or IDxxx, or DByy.DBDxxx. And you must format that address as a REAL (right click on the I or Q address to open the symbol table, mark it as REAL).

Try it...

Hope this helps,

Daniel Chartier

 

Hello oluwasego;

You receive strange values, you say? How are they strange? For example, if you send 1.0, do you receive somethong like 3 649 e+37?

If that is the case, you have a Big Endian/ Little Endian problem, because the processors on your PLCs follow one the Motorola convention, the other the Intel convention. The problem is related to the order of bytes exchanged that are inverted.

Look at the Step 7 v1x instruction SWAP to reorder the bytes in the S7-1500, use it on your Real variables received from the Beckhoff PLC. Try it with a single Real, see how the 8nstruction works, and the results you get.

Hope this helps, 

Daniel Chartier 

 Hello Daniel,

Thank you very much for your prompt input. Yes, when data like 100 is sent from the Beckhoff, I get values like 16#0000_00042, 1.839078E-38, etc

The problem is, I have not even loaded them into a DB. I only check from the Input address using %IB, %ID...

dchartier

Hello oluwasego;

You receive strange values, you say? How are they strange? For example, if you send 1.0, do you receive somethong like 3 649 e+37?

If that is the case, you have a Big Endian/ Little Endian problem, because the processors on your PLCs follow one the Motorola convention, the other the Intel convention. The problem is related to the order of bytes exchanged that are inverted.

Look at the Step 7 v1x instruction SWAP to reorder the bytes in the S7-1500, use it on your Real variables received from the Beckhoff PLC. Try it with a single Real, see how the 8nstruction works, and the results you get.

Hope this helps, 

Daniel Chartier 

Hello oluwasego;

As stated earlier, the instructio. SWAP should be helpful in this case.

Use any one of your expe ted Real inputs, %ID25 for example, as input to the SWAP instruction, use your DB address as the output parameter. Check if the swapped value is what you expected.

Hope this helps,

Daniel Chartier 

 Hi Daniel, thank you once again.

I tried that, however, the SWAP function only takes WORD or INT data types

My %ID21 = 16#0000_C842

While %IB and %IW = 0

dchartier

Hello oluwasego;

As stated earlier, the instructio. SWAP should be helpful in this case.

Use any one of your expe ted Real inputs, %ID25 for example, as input to the SWAP instruction, use your DB address as the output parameter. Check if the swapped value is what you expected.

Hope this helps,

Daniel Chartier 

Hello oluwasego;

Here is a description of the SWAP nstruction in Step  v16. You are right, the input can be eiher a Word ofr a DWord, it does not accepyt a REAL. 

https://support.industry.siemens.com/cs/ww/en/view/109773506/101023978763

BUT: User A_Dent had a similar issue as yours, with a Beckhoff PLC exchanging Real variables with a S7 PLC. Here you will find his description of the SWAP instruction in this case:

https://support.industry.siemens.com/tf/ww/en/posts/issue-handling-real-inputs/213129/?page=0&pageSize=10

Hope this helps,

Daniel Chartier

 Hello Daniel,

THANK YOU VERY MUCH!

I have been able to get the SWAP function right. I used a combination of the SWAP and the SLICING methods.

1- I created an FB for the slicing "Edian Conversion"

2- I created tags of MB with datatypes as Bytes. Then I moved the Input bytes from the DP inputs to this MBs. I also created an MD area output as DWORD tags. Since the SWAP function inly takes DWORD or WORD

3- I then used the MBs as input to my FB and the output as the MD.

4- I passed this MD (Dword) as input to the SWAP function and the output to the Conversion. The CONV is used to convert the DWORD to REAL in my DB. The SWAP function does the main job here!

My solution is shown in the image for those who might need it.

Thanks you once again.

References:

(1) https://support.industry.siemens.com/tf/ww/en/posts/issue-handling-real-inputs/213129/?page=0&pageSize=10

( 2) https://support.industry.siemens.com/tf/ww/en/posts/swap-of-word-inside-real/123668

dchartier

Hello Oluwasedago;

Here is a description of the SWAP nstruction in Step  v16. You are right, the input can be either a Word ofr a DWord, it does not accepyt a REAL. 

https://support.industry.siemens.com/cs/ww/en/view/109773506/101023978763

BUT: User A_Dent had a similar issue as yours, with a Beckhoff PLC exchanging Real variables with a S7 PLC. Here you will find his description of the SWAP instruction in this case:

https://support.industry.siemens.com/tf/ww/en/posts/issue-handling-real-inputs/213129/?page=0&pageSize=10

Hope this helps,

Daniel Chartier

Hello oluwasedago;

My congratulations;

Not only have you found a solution to a complex data exchange between different makes of PLCs, but you have shared the solution with us in a clear, researched and generous fashion.

Until next time,

Daniel Chartier