Rockwell Automation 1747-PCIS API Software - Open Controller - Manual (Page 105)

Publication 1747-UM002A-US-P - June 2000
Library of Routines 6-45
The MsgID member of the msgbuf structure will be one of the
following values:
The data returned in the MsgData member array depends upon the
value in MsgID :
Separate queues hold messages received from each source. The host
application must call OC_PollScanner periodically to read messages
from each enabled source to prevent messages from being discarded.
If a message queue is full when a new message is received, the oldest
message is discarded and the next call to OC_PollScanner results in a
return value of ERR_OCOVERRUN. The queue can hold as many as
five messages.
Return Value:
Considerations:
Supported in the DOS API library and the Windows NT API library
This value: Means:
OCMSG_NONE No message available
OCMSG_IOINIT I/O module interrupt message, see OC_SetModuleInterrupt
OCMSG_DIINT Discrete input interrupt message, see OC_ConfigureDII
OCMSG_EOS_DMDIN End-of-scan notification message from OC_DemandInputScan
command, see OC_EnableEOSNotify
OCMSG_EOS_DMDOUT End-of-scan notification message from OC_DemandOutputScan
command, see OC_EnableEOSNotify
OCMSG_EOS End-of-scan notification message for timed I/O scan, see
OC_EnableEOSNotify
This MsgID : Returns:
MsgID=OCMSG_IOINT
MsgData[0]
slot number that generated the interrupt
MsgID=OCMSG_DIINT MsgData[0 ] mask of last bit transition that generated the interrupt
MsgData[2 ] lowbyte of count of matches that generated
the interrupt
MsgData[3]
highbyte of count of matches that generated
the interrupt
MsgID=OCMSG_EOS_DMDIN
MsgID=OCMSG_EOS_DMDOUT
MsgID=OC_EOS MsgData[0] number of scans that occurred since the last
end-of-scan message of this type was read
Name: Value: Description:
SUCCESS 0 scanner was polled successfully
ERR_OCACCESS 2 handle does not have access to scanner
ERR_OCOVERRUN 16 a message has been discarded