ProSoft Technology MVI69-ADM - Manual (Page 312)

Side-Connect API Library Functions MVI-ADM ♦ 'C' Programmable
Developer's Guide 'C' Programmable Application Development Module
Page 312 of 342 ProSoft Technology, Inc.
February 20, 2013
MVIsc_RMWPLC
Syntax
int MVIsc_RMWPLC(HANDLE handle, WORD and_mask, WORD or_mask, WORD fileno, WORD
elemno, WORD subelemno);
Parameters
handle Handle returned by previous call to MVIsc_Open
and_mask Bits to be preserved in the data item
or_mask Bits to be set in the data item
fileno
PLC-5 data table file number
elemno PLC-5 data table element number
subelemno PLC-5 data table subelement number
Description
MVIsc_RMWPLC reads a word from a PLC-5 data table, modifies some of the
bits, and then writes it back.
handle must be a valid handle returned from MVIsc_Open. and_mask specifies
the bits to be preserved in the data word. A "1' bit preserves the corresponding
bit in the data word; a "0' bit forces the corresponding bit to zero. or_mask
specifies the bits to be set in the data word. A "1' bit forces the corresponding bit
in the data word to 1; a '0' bit leaves the corresponding bit unchanged. The
or_mask is applied after the and_mask.
fileno and elemno specify the data table file number and element number of the
data word to be modified. subelemno is used to address structured data. It
specifies the offset to a particular data word within a multi-word data structure,
such as a PID structure. For simple data files such as integer, subelemno must
be set to zero; otherwise, no data will be written and MVISC_ERR_XFERFAIL
will be returned. subelemno is specified as the word offset within the data
structure.
Note: For convenience, sub-element definitions for each of the data items within the various PLC-5
data structures are provided in the API include file MVISCAPI.H.
Notes: An attempt to access past the end of a data table file will result in a return code of
MVISC_ERR_XFERFAIL or MVISC_ERR_PCCCFAIL. If the PLC is in RUN mode when this
access is attempted, PLC-5 data will be corrupted and the PLC-5 will be faulted. Care should be
taken not to exceed the boundaries of the PLC-5 data tables. See MVIsc_GetPLCFileInfo to
determine valid data table boundaries.
Return Value
MVISC_SUCCESS The data was written successfully
MVISC_ERR_NOACCESS handle does not have access
MVISC_ERR_BADPARAM Parameter contains invalid value