PRB: Can't Receive Data When Using MSCOMM.OCX Control (141071)


The information in this article applies to:

  • Microsoft Visual Basic Standard Edition, 32-bit, for Windows 4.0
  • Microsoft Visual Basic Professional Edition, 16-bit, for Windows 4.0
  • Microsoft Visual Basic Professional Edition, 32-bit, for Windows 4.0
  • Microsoft Visual Basic Enterprise Edition, 16-bit, for Windows 4.0
  • Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows 4.0
This article was previously published under Q141071

SYMPTOMS

While performing serial communications by using the MSCOMM16.OCX or MSCOMM32.OCX control, you can get it to connect and send data, but not receive data.

CAUSE

You do not have the correct handshaking enabled.

RESOLUTION

To resolve this problem when using MSCOMM.OCX, set the RTSEnable property to True or add the following line of code to your program when you initialize the MSCOMM control: 
   MSComm1.RTSEnable = True

MORE INFORMATION

The following information on the RTSEnable property comes from the Custom Control Help file (CTRLREF.HLP):

(RTSEnable) Determines whether to enable the Request To Send (RTS) line. Typically, the Request To Send signal that requests permission to transmit data is sent from a computer to its attached modem.

When RTSEnable is set to True, the Request To Send line is set to high (on) when the port is opened and low (off) when the port is closed. The Request To Send line is used in RTS/CTS hardware handshaking. The RTSEnable property allows you to manually poll the Request To Send line if you need to determine its state.

Modification Type:MajorLast Reviewed:12/9/2003
Keywords:kbprb KB141071
©2003 Microsoft Corporation. All rights reserved.