General Information
With TB_FIFO (first in, first out), data records are saved sequentially and can be read out again in the same order at a later time. Up to 256 data records can be saved.
When x_Enable = TRUE, the module is activated. Successful activation is signaled with TRUE at the x_Active output. From this point, data records can be saved and read. A data record consists of one to four data words.
Saving data:
The data record active at di_InVal0..3 is saved with the positive edge at input x_Put. If the data record was accepted, this is reported with TRUE at the x_PutDone output for one cycle. If the data record could not be saved (FIFO full), x_PutDone remains FALSE and an error is output. Up to 256 data records can be saved.
Reading data:
With a positive edge at the x_Get input, the oldest data set is read, output at di_OutVal0..3 and deleted internally. This means that a read data record cannot be read out a second time. Successful output is indicated with TRUE at the x_GetDone output for one cycle. If no data records could be read (FIFO empty), x_GetDone remains FALSE and an error is output.
Deleting FIFO:
When the enable is cancelled (x_Enable = FALSE), the FIFO is deleted and all saved data records are deleted.
Acknowledging errors:
Errors are deleted automatically via a valid command. If, for example, a data record is saved after an error -2 (FIFO empty), x_Error becomes FALSE and i_Error becomes 0.
| Recommended task: | Event / Cyclic |
| Libraries used: | - |
InOut Parameter
| none |
Input Parameter
| Marking: | Data type: | Description: |
|---|---|---|
| x_Enable | BOOL | TRUE: Enabling of the module and deleting of the FIFO. Successful enabling is indicated at x_Active. |
| x_Get | BOOL | With the positive edge, the oldest data record is output at di_OutVal0..3. Successful output is indicated at x_PutDone. |
| x_Put | BOOL | With the positive edge, the data record is accepted at di_InVal0..3. Successful acceptance is indicated at x_PutDone. |
| di_InVal0 | DINT | First data word of the data record entered in the FIFO. |
| di_InVal1 | DINT | Second data word of the data record entered in the FIFO. |
| di_InVal2 | DINT | Third data word of the data record entered in the FIFO. |
| di_InVal3 | DINT | Fourth data word of the data record entered in the FIFO. |
Output Parameter
| Marking: | Data type: | Description: |
|---|---|---|
| x_Active | BOOL | TRUE: Module active. Data records can be written and read. |
| x_GetDone | BOOL | TRUE: Indicates that the data output at di_OutVal0..3 is valid for one cycle. |
| x_PutDone | BOOL | TRUE: Indicates that the data active at di_InVal0..3 is accepted for one cycle. |
| di_OutVal0 | DINT | First data word of the data record read out of the FIFO. |
| di_OutVal1 | DINT | Second data word of the data record read out of the FIFO. FALSE: when error list was created successfully |
| di_OutVal2 | DINT | Third data word of the data record read out of the FIFO. |
| di_OutVal3 | DINT | Fourth data word of the data record read out of the FIFO. |
| i_Elements | INT | Number of data records currently saved in FIFO. |
| x_Error | BOOL | TRUE: An error was identified. |
| i_Error | INT | Current error number. See table above. |
| i_Error | Description |
|---|---|
| 0 | No error |
| -1 | Write error. An attempt was made to write a data record, even though FIFO is full. |
| -2 | Read error. An attempt was made to read a data record, even though FIFO is empty. |