This page is a part of VPortPro online Help Manual.
VPortPro-client with Com Port Control by Labtam.
VPortPro makes serial (RS232) data from your PC available on TCP/IP-based networks and makes TCP/IP data available on virtual serial ports of your PC. Visit Home of VPortPro for more information.



COM-port Settings

When you click the Initial settings button in the Add dialog the COM-port settings dialog box brings up:

This dialog is used to set up the configuration parameters for the current COM port to their default or desired values (these are initial values because they may be changed when establishing connection in the Telnet RFC-2217 protocol mode). These are Bits per second, Data bits, Parity, Stop bits, and Flow control. For COM port options, the settings must match the COM port behavior expected by the PC application that will use this COM port.

Default

This button is used to reset the configuration parameters for the current COM-port to their default values.

For more information, refer to Appendix B. Serial Connection Overview.

Bits per second

Specifies the transmission rate in bits per second. You can choose an appropriate value from the list box. The default value is 9600.

The speed at which devices transmit data is called the throughput. This is measured in bits per second (bps). Bits per second is the number of bits transmitted every second, used as a measure of the speed at which a device can transfer data. A character is made up of 8 bits. In asynchronous communication, each character may be preceded by a start bit and may terminate with a stop bit. So for each character, 10 bits are transmitted. For example, if a device communicates at 2,400 bits per second, then 240 characters are sent every second.

For serial communications, speed in bits per second can be divided by 10 to approximate the characters transmitted per second.

Data bits

Specifies the number of data bits in a character. Most systems now use 8 bits to represent a single data character (extended ASCII). In rare instances, some older systems still use 7 bits. Valid values for data bits are in the range 5 through 8. The default value is 8. Not all computers support the values 5 and 6. You can choose an appropriate number from the list box.

Parity

Specifies how the system uses the parity bit to check for transmission errors.

The parity value can be set to one of the following:

None

Send no parity bit.

Even

Set the parity bit to 0 or 1 to make the number of 1 bits even.

Odd

Set the parity bit to 0 or 1 to make the number of 1 bits odd.

Mark (1)

Set the parity bit always to 1.

Space (0)

Set the parity bit always to 0.

The default value is None. You can choose an appropriate value from the list box. Not all computers support the values Mark and Space. Most modem connections now use more reliable and sophisticated methods of error checking, so this is usually set to None.

Stop bits

Specifies the number of stop bits that define the end of a character: 1, 1.5, or 2. You can choose an appropriate number from the list box. The default value is 1. If the baud rate is 110, the default value is 2; otherwise, the default value is 1. Not all computers support the value 1.5.

Flow control

From within the list box, you can choose one of the following:

XON/XOFF

Specifies whether the XON or XOFF protocol for data-flow control is on or off.

Software flow control (also called XON/XOFF or CTRL+S/CTRL+Q) uses data characters to indicate that the data flow should start or stop. This enables a device to send a control character to signal another device to stop transmitting while it catches up.

Software flow control is slower and usually less desirable than hardware flow control. Software flow control is used only for transmitting text. It cannot be used for binary file transfer because binary data may contain the special flow control characters.

Hardware

Hardware flow control (RTS/CTS) depends on the device to control the flow of data. This should be used with all high-speed modems or modems that compress data.

RTS specifies whether the Request To Send circuit is set to on, off, handshake, or toggle.

CTS specifies whether output handshaking that uses the Clear To Send circuit is on or off.

None

No flow control options will be used (the default value).

Note

When you want to "connect" a serial data source with a serial data destination (e.g., across the network or as two virtual serial ports), make sure that the serial port settings on both sides of such a "connection" be matched.


The Extra String Box

In the Extra String box, you can specify the following edit fields:

Connection

When the TCP/IP connection gets established, the bytes sequence you specified in the field will first be sent to the COM port.

Disconnection

When the TCP/IP connection gets closed, the bytes sequence you specified in the field will finally be sent to the COM port.

These options may be useful if the TCP/IP client is suddenly disconnected from the TCP/IP server while attached via VCOM-TCP Primary Client to one of remote sites. To disconnect the modem from the remote site on the unattended server, this is a way to be able to drop DTR, etc.




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