Rockwell Automation 1771-DMC_DMC1_DMC4_DXPS Control Coprocessor User Manual - Manual (Page 137)

API Library of Routines
Appendix B
BPI_READ
B-6
Returns
Status Symbolic Name Meaning
0 CC_SUCCESS Operation successful
118 CC_E_TIME I/O operation did not complete in time
160 CC_E_INV_TO Invalid timeout value
164 CC_E_INV_BPI_MASK Invalid valuefor BPI trigger mask
190 CC_E_SIZE Invalid sizefor operation
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 */
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status = BPI_READ (size, inbuff, timeout, trg_mask);
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