Profibus Dp; Accessing The Process Image; Example - WAGO -I/O-SYSTEM 750 Series Manual

4.4 PROFIBUS DP

4.4.1 Accessing the process image

The data in the AS-Interface master is accessed via the process image of the
PROFIBUS master. To ensure data consistency at a 12 to 48-byte data width,
the data must be mapped with system functions for consistent reading and
writing in an appropriately sized array. The PLC program can then process the
data in this array.
4.4.1.1

Example

Let a node contain the following modules with an input / output process
image:
3 x 750-402
1 x 750-452
1 x 750-655
1 x 750-550
1 x 750-452
1 x 750-550
1 x 750-452
1 x 750-504
The AS-Interface master module occupies a process image of 12 bytes when
the mailbox size is 6 bytes. The mailbox is permanently superimposed.
In the PROFIBUS master, the I/O configuration can be designed as follows:
WAGO-I/O-SYSTEM 750
I/O Modules
each with 4 bits of input data,
4 bytes of input data,
12 bytes of input data and 12 bytes of output data,
4 bytes of output data,
4 bytes of input data,
4 bytes of output data,
4 bytes of input data,
4 bits of output data.
No. Function
1 Digital input
Digital input
Digital input
Digital input
2 Digital input
Digital input
Digital input
Digital input
3 Digital input
Digital input
Digital input
Digital input
4 Analog input
Analog input
Fieldbus-specific behavior
Module
Identification
750-402 4 DI/24 V DC/3.0 ms
0x10
*750-402 4 DI/24 V DC/3.0 ms
0x00
750-402 4 DI/24 V DC/3.0 ms
0x10
750-452 2 AI/0-20 mA/diff.
0x51
PROFIBUS DP
PI Master *
Inputs Outputs
IB12.0
IB12.1
IB12.2
IB12.3
IB12.4
IB12.5
IB12.6
IB12.7
IB13.0
IB13.1
IB13.2
IB13.3
IW0
IW2
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