Rockwell-automation 1771-DMC_DMC1_DMC4_DXPS Control Coprocessor User M Manual de usuario descargar pdf (Pagina 259)

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Appendix B

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B-128

Description

Use the TAG_READ_W function to read data from a tagged memory area.

This function waits until a corresponding TAG_WRITE_W function is

posted. More than one TAG_READ_W can be pending on a single

TAG_WRITE_W. This function guarantees that the read data area is

semaphored during the read operation.

C Example

unsigned my_fred;

unsigned status;

status = TAG_READ_W (“Fred”,0,sizeof(my_fred),&my_fred,30);

BASIC Example

The BASIC function code is 65.

DIM status : INTEGER

DIM tag_id : INTEGER

DIM my_data : INTEGER

rem * TAG_READ_W - read 4 bytes from a tag, starting at offset 0 into

rem * my_data with a timeout of 30 seconds. The read will

rem * not proceed until the specified tag has been written

rem * to by TAG_WRITE_W.

RUN AB_BAS (65,status,tag_id,0,4,ADDR(my_data),30)

References

TAG_LINK(); TAG_DEFINE(); TAG_UNDEF();

TAG_GLOBAL_UNDEF(); TAG_WRITE(); TAG_LOCK();

TAG_UNLOCK(); TAG_READ(); TAG_WRITE_W();

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Rockwell-automation 1771-DMC_DMC1_DMC4_DXPS Control Coprocessor User M Manual de usuario Pagina 259