Local process image in delivery state

The process image of the BX/BCxx50 consists of an input, output and flag area. In addition, there are unallocated data without fixed address. They are created without specifying an address. For this type of variable 256/48 kB of memory are available on the BX/BCxx50. The maximum size of a variable or structure (array) is 16 kbyte. For the allocated data 2048 bytes of input data and 2048 bytes of output data are available. The BX/BCxx50 has 4 kB of memory for the allocated flag area. In the delivery state (default configuration) of the BX/BCxx50, fixed addresses are allocated for all connected Bus Terminals. The data for fieldbus communication start from address offset 1000dec. The fieldbus data length depends on the fieldbus system used.

Inputs

Outputs

Bus Terminal %IB0 ...

Bus Terminal %QB0 ...

Fieldbus data (PLC variables) %IB1000 ...

Fieldbus data (PLC variables) %QB1000 ...

...  %IB2047 maximal

...  %QB2047 maximal

Differences in the protocols

The data for the higher-level master, Modbus or KS8000 protocol are stored in the BC8150 from address 1000. For Modbus the maximum data length is 512 bytes and does not have to be set within the range 1 to 126 words. For the KS8000 protocol the number of data from address 1000 is preset to 8 words or 16 bytes inputs and 8 words or 16 bytes outputs. The BC8150 will reject data telegrams that do not match this number exactly and issue an error. This data length can be parameterized via a function block in the BC8150.

If the Modbus protocol is used, data access to the BC8150 flag area is recommended. This area can be read and or written to without triggering the watchdog. The ADS protocol can access all data. The whole process image can be accessed via port 800, and the process image from address 1000 via port 300. If port address 800 is used, the data are only available for read access. If the serial ADS is used, it is recommended to access the flag area that can be reached via port 800 and IndexGroup 0x4020.

Addressing of the connected Bus Terminals

The default setting is for all the connected Bus Terminals to be assigned to the local process image. Mapping within the Bus Terminal Controller is carried out according to the following rule:
First all the complex Bus Terminals, in the sequence they are physically inserted, followed by the digital Bus Terminals which are filled to a byte. The default mapping of the complex Bus Terminals is:

Example structure

Bus Terminal Controller: 1 x BX/BCxx50
Position 1: 1 x KL1012
Position 2: 1 x KL1104
Position 3: 1 x KL2012
Position 4: 1 x KL2034
Position 5: 1 x KL1501
Position 6: 1 x KL3002
Position 7: 1 x KL4002
Position 8: 1 x KL6001
Position 9: 1 x KL9010

Process image

Bus Terminal

Position

Input image

Output image

KL1501

5

%IB0...%IB5

%QB0...%QB5

KL3002

6

%IB6...%IB13

%QB6...%QB13

KL4002

7

%IB14...%IB21

%QB14...%QB21

KL6001

8

%IB22...%IB29

%QB22...%QB29

KL1012

1

%IX30.0..30.1

-

KL1104

2

%IX30.1..30.5

-

KL2012

3

-

%QX30.0..30.1

KL2034

4

-

%QX30.2..30.5

KL9010

9

-

-

 

Local process image in delivery state 1:

Show associated variables

If you do not know the address of the Bus Terminals that you have assigned to the local PLC (BX/BCxx50):
Perform your hardware configuration in the System Manager. After you have entered all the Bus Terminals and PLC variables, click with the right mouse button on the BX/BCxx50 in the hardware tree, and select the menu item Export variables information.... A file is saved, and this file can be inserted in the System Manager under Project - Import. Now you will have the entry TwinCAT import under the global variables, and you will find here all the variables that you have assigned to the local PLC (BX/BCxx50).