Addressing

S7TCP32 -> Creating variables -> Addressing
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The address resolution of the driver is BYTE-based, therefore SINT. When addressing INT and UINT variables, address in steps of two, for DINT and UDINT in steps of four. You can address single bits by adding the bit number.

Settings for the unique addressing of variables

Property

Description

Name

Any name may be chosen. ATTENTION: the name must be unique within every control system project.

Identification

Any text can be entered here, e.g. for resource labels, comments ...

Net address

Bus address or net address of the variable.
This address refers to the bus address in the connection configuration of the driver. This defines the PLC, on which the variable resides.

Data block

For variables of object type Extended data block, enter the datablock number here. Configurable [0.. 4294967295] . Please look up the exact maximum range for data blocks in the manual of the PLC.

Offset

Offset of the variable; the memory address of the variable in the PLC. Configurable [0.. 4294967295]
Most S7 PLCs support a maximum Offset of 65535. Please look up the exact maximum range for objects in the manual of the PLC.

Alignment

not used for this driver

Bit number

Number of the bit within the configured offset.
Allowed entry [0.. 65535], Working range [0..7]

String length

Only available for String variables: Maximum number of characters that the variable can take.

Driver object type

Depending on the employed driver, an object type is selected during the creation of the variable; the type can be changed here later.

Data type

Data type of the variable, which is selected during the creation of the variable; the type can be changed here later.
ATTENTION: If you change the data type later, all other properties of the variable must be checked and adjusted, if necessary.

Example

- For addressing double word (DINT/UDINT) variables:
The connection was configured with net address 2. Two double words in data block 33 in a row starting from offset 20.

Addressing double word 1:

Net address:

2

Data block:

33

Offset:

20

Driver object type:

Ext. data block

Data type:

UDINT (DINT)

Addressing double word 2:

Net address:

2

Data block:

33

Offset:

24

Driver object type:

Ext. data block

Data type:

UDINT (DINT)

- For addressing bit (BOOL) variables:
The connection was configured with bus address 2. One marker bit with offset 79, the fourth bit.

Net address:

2

Data block:

Not used

Offset:

79

Bit number:

3 (bits are counted from 0)

Driver object type:

PLC marker

Data type:

BOOL