Rockwell-automation 1747-PCINT API Software for 1746 I/O Uživatelský manuál stáhnout pdf (Strana 105)

OC_PollScanner Library of Routines 6–51

Publication 1747-6.5.3 June 1998

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

Example:

HANDLE Handle;

MSGBUF msgbuf;

int retcode;

retcode = OC_PollScanner( Handle, OCMSG_ANY, &msgbuf );

/* Check msgbuf.MsgID for what message is available */

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

scanner was polled successfully

ERR_OCACCESS

handle does not have access to scanner

ERR_OCOVERRUN

a message has been discarded

1 2 ... 100 101 102 103 104 105 106 107 108 109 110 ... 154 155

Žádné komentáře

Rockwell-automation 1747-PCINT API Software for 1746 I/O Uživatelský manuál Strana 105