Technical data

8.1.3 Handling the Individual Data Transmission Services from the

Point of View of the Control Program

The SEND block can be used to transfer an FDL request. FDL

confirmations or FDL indications are accepted in the PLC with a RECEIVE

HDB. Via the bits in the status word which can be updated with the

CONTROL block, the SEND or RECEIVE HDBs can be controlled.

The status word contains information about the status of a job, information

about data management and error bits. In the figures illustrating the

sequence of the control program (refer to Figs. 8.7 to 8.11) the change in

the status word (ANZW) is always visible.

8.1.4 Checking the Data Transmission in the Control Program

using ANZW and PAFE

If messages are sent by a PLC, the PLC expects an acknowledgment. This

acknowledgment can be either positive or negative and simply indicates

whether the frame arrived at the communications partner or not. The

acknowledgment provides information about the processing status of the

frame and can be evaluated from the updated status word (ANZW) of the

CONTROL/SEND/RECEIVE HDBs.

The status word informs you about the following:

➣

the status of the job

➣

the data management

➣

any errors

Following synchronization, the status words of all the links (ANR) assigned

parameters with COM 5430 TF/COM 5431 FMS contain the value 0008

. If

the link was not defined, the ANZW has the value 0F0A

B8976060/02 Free Layer 2 Communication

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