Thread: Difference between mscomm control in VB and hyperterminal

Hi Friends,

I am new to this forum and I am trying to create an application with mscomm control in VB6.
I created an serial port application in VB6. It sends some message to an ABB PLC and receives some data from the PLC. The vb application works for 1 cycle. for the second cycle the application does not receive any data, Where as if I check using the hyperterminal connectivity, then it allows 'n' cycles with the similar data.

Can any one tell me what is the problem and how this can be rectified.

The following is the portmonitor output.

411 0.00004867 vb6.exe IRP_MJ_CREATE Serial0 SUCCESS Options: Open
412 0.00000305 vb6.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING
413 0.00000119 vb6.exe IOCTL_SERIAL_SET_QUEUE_SIZE Serial0 SUCCESS InSize: 1024 OutSize: 512
414 0.00000327 vb6.exe IOCTL_SERIAL_PURGE Serial0 SUCCESS Purge: TXABORT RXABORT TXCLEAR RXCLEAR
415 0.00000109 vb6.exe IOCTL_SERIAL_SET_TIMEOUTS Serial0 SUCCESS RI:-1 RM:0 RC:0 WM:0 WC:5000
416 0.00000971 vb6.exe IOCTL_SERIAL_GET_BAUD_RATE Serial0 SUCCESS
417 0.00000166 vb6.exe IOCTL_SERIAL_GET_LINE_CONTROL Serial0 SUCCESS
418 0.00000133 vb6.exe IOCTL_SERIAL_GET_CHARS Serial0 SUCCESS
419 0.00000133 vb6.exe IOCTL_SERIAL_GET_HANDFLOW Serial0 SUCCESS
420 0.00000104 vb6.exe IOCTL_SERIAL_GET_BAUD_RATE Serial0 SUCCESS
421 0.00000306 vb6.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING
422 0.00000127 vb6.exe IOCTL_SERIAL_GET_LINE_CONTROL Serial0 SUCCESS
423 0.00000203 vb6.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING
424 0.00000145 vb6.exe IOCTL_SERIAL_GET_CHARS Serial0 SUCCESS
425 0.00000112 vb6.exe IOCTL_SERIAL_GET_HANDFLOW Serial0 SUCCESS
426 0.00026034 vb6.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 SUCCESS
427 0.00000856 vb6.exe IOCTL_SERIAL_SET_BAUD_RATE Serial0 SUCCESS Rate: 9600
428 0.00000366 vb6.exe IOCTL_SERIAL_SET_RTS Serial0 SUCCESS
429 0.00000377 vb6.exe IOCTL_SERIAL_SET_DTR Serial0 SUCCESS
430 0.00000260 vb6.exe IOCTL_SERIAL_SET_LINE_CONTROL Serial0 SUCCESS StopBits: 1 Parity: NONE WordLength: 8
431 0.00000125 vb6.exe IOCTL_SERIAL_SET_CHAR Serial0 SUCCESS EOF:1a ERR:0 BRK:0 EVT:0 XON:11 XOFF:13
432 0.00000325 vb6.exe IOCTL_SERIAL_SET_HANDFLOW Serial0 SUCCESS Shake:80000001 Replace:80000040 XonLimit:256 XoffLimit:256
433 0.00000155 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
434 0.00002699 vb6.exe IRP_MJ_WRITE Serial0 SUCCESS Length 5: 105..
435 0.00000192 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
436 0.00000390 vb6.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING
437 0.01034396 vb6.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 SUCCESS
438 0.00000177 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
439 0.00000192 vb6.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING
440 0.00000334 vb6.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 SUCCESS
441 0.00000161 vb6.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING
442 0.00000222 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
443 0.01384521 vb6.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 SUCCESS
444 0.00000150 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
445 0.00000343 vb6.exe IRP_MJ_READ Serial0 SUCCESS Length 5: 105..
446 0.00000130 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
447 0.00000123 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
448 0.00000122 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
449 0.00000164 vb6.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING
450 0.00000320 vb6.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 SUCCESS
451 0.00000185 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
452 0.00000233 vb6.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING
453 8.96522003 vb6.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 SUCCESS
454 0.00000153 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
455 0.00000283 vb6.exe IRP_MJ_READ Serial0 SUCCESS Length 5: ..RTS
456 0.00000140 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
457 0.00000180 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
458 0.00000123 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
459 0.00000677 vb6.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING
460 0.00000363 vb6.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 SUCCESS
461 0.00000180 vb6.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING
462 0.00000811 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
463 0.01025482 vb6.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 SUCCESS
464 0.00000180 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
465 0.00000460 vb6.exe IRP_MJ_READ Serial0 SUCCESS Length 8: ..CS005.
466 0.00000138 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
467 0.00000136 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
468 0.00000133 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
469 0.00000174 vb6.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING
470 0.00000335 vb6.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 SUCCESS
471 0.00000335 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
472 0.00000257 vb6.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING
473 2.21559484 vb6.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 SUCCESS
474 0.00000156 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
475 0.00000322 vb6.exe IRP_MJ_READ Serial0 SUCCESS Length 6: .A2453
476 0.00000125 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
477 0.00000127 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
478 0.00000124 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
479 0.00000620 vb6.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING
480 0.00000372 vb6.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 SUCCESS
481 0.00000728 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
482 0.00000415 vb6.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING
483 0.00818320 vb6.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 SUCCESS
484 0.00000183 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
485 0.00000378 vb6.exe IRP_MJ_READ Serial0 SUCCESS Length 8: ..CC1464
486 0.00000129 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
487 0.00000132 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
488 0.00000122 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
489 0.00000166 vb6.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING
490 0.00000326 vb6.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 SUCCESS
491 0.00000270 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
492 0.00000272 vb6.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING
493 0.00509449 vb6.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 SUCCESS
494 0.00000155 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
495 0.00000334 vb6.exe IRP_MJ_READ Serial0 SUCCESS Length 8: ..B0483.
496 0.00000128 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
497 0.00000183 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
498 0.00000123 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
499 0.00000162 vb6.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING
500 53.85307121 vb6.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 SUCCESS
501 0.00000246 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
502 0.00000128 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
503 0.00000334 vb6.exe IRP_MJ_READ Serial0 SUCCESS Length 1: .
504 0.00000132 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
505 0.00000123 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
506 0.00000545 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
507 0.00000095 vb6.exe IOCTL_SERIAL_GET_PROPERTIES Serial0 SUCCESS
508 0.00003146 vb6.exe IRP_MJ_WRITE Serial0 SUCCESS Length 5: 105..
509 0.00000224 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
510 0.00000524 vb6.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING
511 0.01047579 vb6.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 SUCCESS
512 0.00000198 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
513 0.00000158 vb6.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING
514 0.00000349 vb6.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 SUCCESS
515 0.00000173 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
516 0.00000262 vb6.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING
517 83.99305571 vb6.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 SUCCESS
518 0.00000149 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
519 0.00000384 vb6.exe IRP_MJ_READ Serial0 SUCCESS Length 5: 105..
520 0.00000135 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
521 0.00000122 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
522 0.00000126 vb6.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 SUCCESS
523 0.00002661 vb6.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask:


The communication hangs at this point and I have to reset the communication every time.
I find that similar problems have been faced earlier by others, but still I could not make out the solution.
Can some one help? I need this urgently to complete my degree project work


Thanks in advance.