Echelon OpenLDV - Manual (Page 62)

54 Using the OpenLDV API
if (ldvCmdOk) {
// Build message to send to NI
m_msgOut.ni_hdr.q.queue = niNTQ;
m_msgOut.ni_hdr.q.q_cmd = niNETMGMT;
m_msgOut.ni_hdr.q.length = sizeof(ExpMsgHdr) + sizeof(ExplicitAddr) +
msgSize ;
m_msgOut.msg_hdr.exp.tag = 1; // Assume message tag 1
m_msgOut.msg_hdr.exp.auth = 0;
m_msgOut.msg_hdr.exp.response = 1; // Make it a response
m_msgOut.msg_hdr.exp.st = 3; // Make it a REQUEST
m_msgOut.msg_hdr.exp.pool = 0; // Must be zero
m_msgOut.msg_hdr.exp.alt_path = 0; // Use default path
m_msgOut.msg_hdr.exp.addr_mode = 0; // Implicit addressing
m_msgOut.msg_hdr.exp.cmpl_code = 0; // MSG_NOT_COMPL
m_msgOut.msg_hdr.exp.path = 0; // Use primary path
m_msgOut.msg_hdr.exp.priority = 0;
m_msgOut.msg_hdr.exp.length = msgSize ;
m_msgOut.addr.snd. lc = NI_LOCAL;
m_msgOut.data.code = LonNdQueryStatus;
// Omitting “m_msgOut.data.data” because Query Status command has no data
// Write query status command to the network interface
rc = ldv_write(m_OpenLdvHandle, m_msgOut, offsetof(ExpAppBuffer, code) +
msgSize);
if (rc != LDV_OK) {
ldvCmdOk = FALSE; // Don’t try to read from the network interface
printf(“Could not write to network interface.\n”);
}
else {
ldvCmdOk = TRUE; // Ok to read from the network interface
}
}
if (ldvCmdOk) {
// Wait for network interface event
WaitForSingleObject (hEvent, 1000); // Wait 1 second
// Read response to query status command
rc = ldv_read(m_OpenLdvHandle, &m_msgIn, sizeof(m_msgIn));
if (rc != LDV_OK) {
printf(“Could not read from network interface.\n”);
}
else {
// Read return code from the LonNdQueryStatus command
if (m_msgIn.data.code == LonNdQueryStatusSuccess) {
// Success response from Query Status command;
// Read error log as something interesting to do
BYTE errLog = ( ND_query_status_response *)(&m_msgIn.data.data)->
error_log ;
if (errLog == 0) printf(“No error in network interface.\n”);
else printf(“Network interface error was: %d\n”, errLog);
}
else {
// Failure response from Query Status command; do something else
printf(“Failure response from Query Status cmd: %d\n”,m_msgIn.data.code);
}
}
}