3S - Smart Software Solutions GmbH
CommFB
3.5.18.0
Application|Fieldbus
CommFB
3S - Smart Software Solutions GmbH
CommFB
**Communication Function Blocks on PROFIBUS DP and PROFINET IO**
For PROFIBUS DP and PROFINET IO sets of communication services are defined in IEC 61158. The representation of these services in the application program is dependent of the various controllers and devices provided by different manufactures.
This library implements a set of Communication Function Blocks for communication among programmable controllers and Field Devices over PROFIBUS DP and PROFINET IO respectively.
The following figure gives an overview of the PNO profiles and the placement of this library in the context of the other PNO specifications.
The Communication Function Blocks implemented in this library have a universal interface for PROFIBUS DP as well as PROFINET IO.
Parameters:
Parameters of different Communication Function Blocks with the same or a similar meaning have the same name and data type according the following Table:
|
Parameter |
Data Type |
Meaning |
|
REQ |
BOOL |
Request function |
|
ID |
DWORD |
Identification of a Field Device or a slot / subslot of it |
|
INDEX |
INT |
Identifier of a process data object |
|
OFFSET |
INT |
Count of the first byte within IO Data object |
|
LEN |
INT |
Actual data length of a process data record |
|
DONE |
BOOL |
Flag that the function has finished successfully |
|
VALID |
BOOL |
Flag that the function has finished successfully and the received output data are valid |
|
BUSY |
BOOL |
Flag that the function is still performing its task, its not ready to perform a new task |
|
ERROR |
BOOL |
Flag that the function has finished with an error |
|
STATUS |
DWORD |
Completion or error code |
The actual value of ID should never be manipulated or created, only use the values created from theses sources described here (see: ID). The value of ID can differ depending on the project structure or the driver version !
The INDEX input addresses a process data record, the LEN parameter contains the length of a process data record.
The data type INT is used for both the INDEX and LEN parameter though the value range of the parameters in the IO subsystems may cover 0..65535. The data type INT is supported by all PLC im-plementations, the better fitting UINT is not always supported. The value range of 0..32767 is sufficient for nearly all applications. The data type INT was already used in earlier versions of the library specification, and it is kept for compatibility reason. Nevertheless an INDEX > 32767 may be given on the interface using a negative number or a hexadecimal constant.
The DONE and the ERROR outputs pulses only from one invocation of the instance of the Com-munication Function Block.