Hi,

I am trying to use MB_Client in S7-1200 1212C CPU. Could someone help me / explain to me how can I set up the client to read Swapped FP data type?

I am struggling to understand what to put into MB_DATA_LEN and how to configure MB_DATA_PTR.

I'm getting an error 8383 out of MB_Client whatever I tried so far (data address error or access outside the bounds of the MB_HOLD_REG address area)

I am communicating with an instrument and successfully managed to use MB_CLIENT to read Coil Status (BOOL) without problems.

Attached is ModScan communication showing what I am trying to read on S7-1200 and MB_CLIENT snapshot.

Many thanks for any suggestions.

Ladislav

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Split from Tips and sample program for MODBUS TCP.

Hi All,

I managed to establish valid reading out from the instrument. The issue is how to read swapped FP. Attached is a snapshot showing data received. My information is stored in Read_Modbus[2] and Read_Modbus[1].

The info would be 41C4 0004 but S7-1200 reads it in swapped order (info comes in swapped).

Could anyone help me how to get this read in correct order?

thanks.

LAco_Kuzma

Hi,

I am trying to use MB_Client in S7-1200 1212C CPU. Could someone help me / explain to me how can I set up the client to read Swapped FP data type

 What is FP data type?

You can use rotate/roll  function. If you rotate 8 bits in word, the the hi/lo byte order change. As I have tried time ago the modbus, it is working good. No order swaping is needed, IMO. Rather you can try to make a structure of your variables as you need it, instead of receiving words and then swap. 

I see, FP is floating point. Insert a floating point number instead of words, that's it. You can also mix with different data typesd using structure

STRUCT

fp1: real;

i1:int;

di1: dint;

END_STRUCT

Use a global DB for this (non optimized), don't use M area as you did.

Hi Marko,

Reading Floating point - Real data type gives me a headache because my MB_Client returns error.

Hence I read Words. If I read DWord, I get two in following order - Read_Modbus[0]_Read_Modbus[1] and Read_Modbus[2]_Read_Modbus[3].

Rotate function will not work as my double word is no longer what I want to read.

I am trying to find a way how to create DWord out of two Words in following order- Read_Modbus[2]_Read_Modbus[1].

Any suggestions?

The problem has been resolved.

First, MB_Client is set to store the data in the array of Word(s).

Correct words are then moved into DWord in correct order (if swapped then order swapped).

Then Convert function will convert DWord to Real.

Thanks for ideas.

Hello,

       Could you please upload the project code?

Thanx,

Teo

LAco_Kuzma

Hi All,

I managed to establish valid reading out from the instrument. The issue is how to read swapped FP. Attached is a snapshot showing data received. My information is stored in Read_Modbus[2] and Read_Modbus[1].

The info would be 41C4 0004 but S7-1200 reads it in swapped order (info comes in swapped).

Could anyone help me how to get this read in correct order?

thanks.