Rockwell Automation 1771-DMC_DMC1_DMC4_DXPS Control Coprocessor User Manual - Manual (Page 221)

API Library of Routines
Appendix B
MSG_READ_HANDLER
B-90
Handles a PLC-5 programmable-controller message-read instruction.
C Syntax
#include <copro.h>
unsigned MSG_READ_HANDLER (variable,buff_size,msg_num,
items,timeout, CC_type, plc_type, iostat)
short *variable;
unsigned buf_size;
unsigned msg_num;
unsigned items;
unsigned timeout;
unsigned cc_type;
unsigned plc_type;
int *iostat;
Parameters
variable
Address of a buffer that has the data to be read.
buff_size
Size of the read buffer in bytes.
msg_num
Number of the PLC-5 programmable controller message (0-31).
items
Number of data items to be read by the PLC-5 programmable controller.
The number and size of items cannot be greater than 240 bytes—e.g.,
maximum of 60 floating-point values of 4 bytes each = 240 bytes.
timeout
Timeout value in seconds. When using a value of CC_FOREVER
(defined in COPRO.H), this function will keep the read handler posted
until a message has been received.
MSG_READ_HANDLER