March 10th 1997 Mirror Sites ![]() Download the Software Network Card Drivers ![]() Features User's Guide Help ![]() Search Distribution Rights Listserv Shareware Links ![]() Order the Software Help Us Promote NetSoft LAN Dealer Enquires Welcome Home Page | http://www.netsoft.ie/ CHAPTER 7 The Cummunications RedirectorThe purpose of the communications redirector is to enable you to use a server's serial ports from a client machine. This means that you may use the server's modem, without the need for dedicated network communications-software running on the server machine. The communications redirector works by intercepting the PC BIOS INTERRUPT 14H calls on the client machine, and redirecting them to the server machine. The resulting data or status is returned to the client machine. The communications redirector program (COMREDIR.COM) only works with communications-software that use the PC BIOS INTERRUPT 14H calls. Any software that accesses the serial port directly (through the I/O port address) cannot be used to control the server's serial port devices. The COMREDIR.COM program must be loaded on both client, and server, machines. Loading COMREDIR.COMTo load the communications redirector on the server or client machine, type the following at the DOS command line:cd\dosnet comredir You can connect to the server's serial port device using the NET USE command, or the Station Manager. The server's serial port must have been previously shared using the NET SHARE command, or through the Station Manager. Sharing a modemTo share a modem on the server, type the following at the server's DOS command line:NET SHARE MODEM=COM1 Connecting to a modemTo connect to the server's shared modem from the client machine, type the following at the client's DOS command line:NET USE COM1 \\SERVER1\MODEM Both the NET SHARE and NET USE commands are explained in detail in Chapter 3 "THE NET COMMAND". Once connected, you may use your communications software as normal, accessing the server's serial port device as a local serial port device. The Communications MenusThe communication redirector's menus are accessed through the DOS-NET Main Menu using the network pop-up keys. These are normally CTRL+ALT+Right Shift keys. From the DOS-NET Main Menu, select COM Port Redirection.The following is a step by step guide to most of the features in the communication redirector's menus. The following examples assume that you have connected to the server's serial port (known by the network name "MODEM") using the NET USE command or Station Manager. Initialising serial portsThe following example initialises the network modem to 2400 baud, no parity, 8 data bits, and 1 stop bit. This is normally expressed as 2400, N, 8, 1.
Viewing serial port status![]()
Flow controlFlow control is a simple form of communications handshaking that is used to control the flow of data from the transmitting machine to the receiving machine. When the receiving machine's buffers are full, that machine must save that data, without losing any additional incoming data.The receiving machine must inform the transmitting machine to stop transmitting while the receiving machine saves the data in its buffers. When the receiving machine has saved the data, communications may then continue. This handshaking is called Flow Control. It gives the receiving machine control over the flow of data.
Modem commandsThe communications redirector includes a comprehensive set of modem commands. These commands are only available if the ModemCmds= parameter in the DOSNET.INI file is set to 1. The modem commands work on Hayes-compatible modems only.
This menu allows you to pop-up over your existing software, and issue commands to the network modem from your client machine. To use a command, simply use the arrow keys to move the bar cursor onto the command, and press the Enter key. Normally, these commands are invoked using the Hayes AT command set from your terminal emulation software.
To auto-dial a number, select that name and number and press the Enter key.
If the call is a voice call, you will be advised to pick up the phone then press any key. This informs the modem to transfer control from the modem to your phone set. If the call is a data connection call, the chatter box is displayed as soon as communications are established.
Unlike terminal emulation software, the chatter box does not transmit any data until you press the Enter key. This allows you to correct mistakes before any text is transmitted. To return to the Modem Commands menu, press the Escape key. [Table of Contents] [Home Page] | |
![]() | ![]() | ![]() |