Rockwell-automation 1771-DMC_DMC1_DMC4_DXPS Control Coprocessor User M Instrukcja Użytkownika Pobierz pdf (Strona 137)

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Appendix B

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B-6

Returns

Status Symbolic Name Meaning

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Description

The BPI_READ routine allows the programmable controller to perform a

block-transfer write over the I/O backplane to the control coprocessor.

It may accomplish a block-transfer write with the control coprocessor by

allowing both a timeout and a trigger mask to be specified. The function

will first do a single transfer with the programmable controller using the

caller’s trigger mask. The function will then return to the caller when

either the block transfer or the timeout occurs. The function will return a

success or fail status. In the case of a fail status, the caller can check the

returned status value to find out why the function failed (i.e., transfer_size

> 64).

The programmable-controller ladder program can monitor the input image

for the control coprocessor to receive the trigger mask. If one of the

user-specified bits goes true, then a block-transfer write to the control

coprocessor can be initiated.

C Example

unsigned char size=6; /* size of block transfer */

short inbuff[32]; /* user location to copy data to */

unsigned int timeout=2; /* user timeout in two seconds */

unsigned short trg_mask=0x400; /* trigger mask, bit 12 (octal) is set */

int status; /* status value of BPI_READ */

status = BPI_READ (size, inbuff, timeout, trg_mask);

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Rockwell-automation 1771-DMC_DMC1_DMC4_DXPS Control Coprocessor User M Instrukcja Użytkownika Strona 137