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Download Siemens HB 131. 10 B Technical data
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Access using the Address in ACCU 1 It changes if one of the following occurs: • another data block is opened or • the program returns to a higher level block after a new data block was opened in the inserted block (see also Section 2.4.2, Range of Validity of Data Blocks). Note In the ISTACK, the address entered in the DBA register appears under the heading "DB-ADD". You normally access data words with the STEP 5 operations L/T DW, L/T DR, L/T DL, L/T DD, A/O/AN/ON/=/S/R Dx.y. You can only use these operations up to data word DW 255. However, by manipulating the DBA register, you can use them to access data words > 255. This is also possible with special function OB 180 (see Section 6.15). Examples Example 1: Effect of the "CX DX 17" operation on the DBA register: Addresses DX 17 1516H 1517H 1518H 5 words block header 1519H 151AH DBA 151BH KH = 0000 DW 0 151CH KH = 0001 DW 1 151DH Fig. 9-5 . . . DW 2 Using the DBA register When DX 17 is called, the address of the memory word in which DW 0 is stored is entered in the DBA register. In this example, the DBA is 4152H. Note: In the ISTACK, the address entered in the DBA register appears under the heading ’DB-ADD’. CPU 928B Programming Guide 9 - 12 C79000-B8576-C898-01
