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Entry type: FAQ Entry ID: 59623719, Entry date: 09/10/2014

In STEP 7 (TIA Portal) and in S7-300/S7-400, how can you implement indirect addressing in an SCL program?

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In the following we explain how to implement indirect addressing in SCL with the S7-300/S7-400.

With the SIMATIC S7-300/S7-400 you have the option of indirect addressing:

  • Indirect addressing of tags
  • Indirect addressing of data blocks

Indirect addressing of tags is like absolute addressing. Instead of the address, you specify an offset in parentheses. For the indirect addressing of data blocks you can also use the "WORD_TO_BLOCK_DB" conversion function.

Fig. 1 shows an example of how to use indirect addressing to access a memory area of a data block in the S7-300/S7-400.

Fig. 1

If you want to access markers, inputs and outputs in S7-300/S7-400 using indirect addressing, you need the instructions "%MX()", "%MB()", "%MW()", "%EX()", "%EB()", "%EW()", "%AX()", "%AB()" and "%AW()". Here it is obligatory to enter the percent symbol prefix. The following figure shows you some examples. 

Fig. 2

Further Information
More information is available in the TIA Portal information system under

Creation Environment

The screens in this FAQ response were created with STEP 7 (TIA Portal) V17.

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