Rockwell Automation 1771-DMC_DMC1_DMC4_DXPS Control Coprocessor User Manual - Manual (Page 71)

Chapter 5
Developing Programs
5-11
Important: For the 1771-DMC1 and -DMC4 modules, the default size
allows you to create 1024 TAGs; the -DMC module default size is zero.
Use the following sections to select the appropriate TAG function for your
application. See Appendix B, Application Program Interface Routines, for
the following information on these TAG functions: description, required
parameters, condition values, and a C program example.
TAGĆTable Configuration Functions
Use these TAG configuration functions to establish a TAG table for TAG
functions:
Table 5.I
TAGĆTable Configuration Functions
Function What It Does
TAG_DEFINE Places a TAG name entry into the TAG table
TAG_UNDEF Removes a TAG name or TAG names from the TAG table
TAG_DEF_AVAIL Determines the number of TAG definitions available in the TAG table
TAG_GLOBAL_UNDEF Removes a TAG or TAGs from the TAG table defined by any process
TAG_LINK Gets a handle (offset) for a TAG table entry
Read and Write Functions
Use these TAG functions to read and write to coprocessor memory:
Table 5.J
TAG Read and Write Functions
Function What It Does
TAG_READ Reads data from a tagged memory area
TAG_READ_W Reads data from a tagged memory area after the tag has been written by TAG_WRITE_W
TAG_WRITE Writes data to a tagged memory area
TAG_WRITE_W Writes data to a tagged memory area, returns only after the tag has been read by TAG_READ_W
Lock/Unlock Functions
Use the TAG_LOCK and TAG_UNLOCK functions as a pair in your
program. The TAG_LOCK function protects against concurrent access to
the tagged area of control-coprocessor memory. The TAG_UNLOCK
function is an unlock to the TAG locked by the TAG_LOCK function.
Important: Failure to use a TAG_UNLOCK function to complement a
TAG_LOCK function in a program may cause the system to hang-up.