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76 Siemens Simatic S7 Driver Online Help

Modifying the Process Database

You must also modify the process database because, with the SI7 driver, digital tags

are restricted to accessing datablocks with a data type of BYTE. In the 6.x S_7

driver, this was not the case. Consequently, you may need to re-evaluate and

reconfigure some portion of the digital blocks in your database. For example,

suppose you have digital blocks configured to access the addresses M0, bit 0 to 15 in

your old database. With the SI7 driver, you must reconfigure these addresses as the

following figure shows.

For more information about how to access S7 hardware memory, refer to

Understanding S7 Hardware Memory Organization.

You cannot only change the data type of misconfigured datablocks however. If

analog blocks are accessing the same points as digital blocks, changing the data type

of these datablocks will alter the range of values the analog tags receive. For

example, if a datablock is configured as a WORD and you change it to a BYTE, the

range of values will change from 0 to 65535 to 0 to 255. This can seriously impact

your application unless you know the configuration was changed.

To correct this situation, set the Hardware Options of your analog blocks to the data

type they require. The hardware option overrides the default data type of the

datablock and provides the range of values you require.

Once you reconfigure the datablocks in your driver configuration and the analog and

digital tags, you must reconfigure your pictures. Modify any data links that reference

Digital Register tags that you changed.

For instructions on changing your process database, refer to Modifying the Process

Database.

Byte 0 Byte 1

Word 0

bit 7 bit 0

Most Significant Byte

bit 7 bit 0

Least Significant Byte

Digital addresses

in the S_7 6.x driver M0:15 ... M0:8 M0:7 ... M0:0

map to

in the SI7 7.x driver M0:7 ... M0:0 M1:7 ... M1:0

1 2 ... 81 82 83 84 85 86 87 88 89 90 91 ... 267 268

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