Rockwell Automation 1771-DMC_DMC1_DMC4_DXPS Control Coprocessor User Manual - Manual (Page 258)

API Library of Routines
Appendix B
TAG_READ_W
B-127
Reads data from a user’s TAG memory area after the TAG is written
by TAG_WRITE_W.
C Syntax
#include
unsigned TAG_READ_W (tag,offset,size,buffer,timeout)
unsigned tag;
or
unsigned char *tag;
unsigned offset;
unsigned size;
unsigned *buffer;
unsigned timeout;
Parameters
tag
Use to access the TAG table. This can be either the symbolic TAG or
the handle returned from a TAG_LINK or TAG_DEFINE call.
offset
A byte offset from the start of the tagged area from which data will
be read.
size
Specifies the number of bytes to read from the tagged area.
buffer
Specifies the buffer to copy the data read from the tagged area.
timeout
Timeout value in seconds (valid range 0-16383). The function will
timeout unless the TAG can be read before the timeout expires. The
TAG may not be able to be read if another process has the TAG locked
or if the corresponding TAG_WRITE_W from another process has not
been issued. A value of CC_FOREVER (defined in COPRO.H) will
cause this function to wait indefinitely until the TAG can be read.
Returns
Value Symbolic Name Meaning
0 CC_SUCCESS Operation successful
120 CC_E_BADID TAG define ID out of range
131 CC_E_TOOBIG Data item is greater than maximum allowed
160 CC_E_INV_TO Invalidtimeout value
171 CC_E_TIME_LOCKED Didnot complete in time, TAG locked
173 CC_E_TIME_NOWRITE Didnot complete in time, TAG not written
176 CC_E_NOTAG TAG not found
TAG_READ_W