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The following files are provided with the Kernel Driver:

File Description
brg.c Baud rate example file
devioctl.h Header for device I/O Control
dtest.exe Test Software
install.txt Installation documentation
mrec.c Half Duplex Receive File example C code
mrec.exe Half Duplex Receive File example program
msend.c Half Duplex Send File example C code
msend.exe Half Duplex Send File example program
mtest.exe Full Duplex Example program
stats.c Prints Driver Statistics from I/O Control call
t1mlink.key Test file using Registry Keys
t1mlink.sys Kernel Mode Driver

The Kernel Driver is a Microsoft Character Device Driver. It is a very efficient code implementation, using minimum of the host processor resources. No transmission protocol is used although data is packaged into HDLC type frames that are of user defined size. Any errors which may occur in the data transmission connection between the two systems are not recovered but, the number of CRC errors may be monitored if needed. If the communications link is of very high quality and if the occasional error can be tolerated in the data, then the Kernel Driver may also be used for data transmission.


The Kernel Driver now supports multiple channels, which is sometimes referred to as bonded channels. A T1/WAN Master is a two-channel device. In some cases it may be desirable to increase the speed of a link by using two pipes. For example, two T1 channels each running at 1.5M bits/sec may be used to transmit data at the combined rate of 3M bits/sec. as if there was one big pipe. The driver performs the multiplexing/de-multiplexing automatically so that the data leaves in the same order as it enters.

This function of the Kernel Driver can be used with multiple cards. For example, three WAN Master cards with six IM-T1-CSU modules installed can give a maximum throughput of 6M bits/sec. This data rate is fast enough for MPEG 2 Full D1 resolution, which gives broadcast quality video. Of course the mux is not restricted to MPEG applications.

A program called DTEST is supplied as a test program. DTEST is used most often to verify that a WAN/T1 Master communications card is operating correctly. A "shorting plug" is used to connect the transmit to receive data and clock for a single board test set-up. It can also be used to test two systems connected back-to-back with a null modem cable. An install.txt file is supplied on the distribution disk which describes the installation and use of this program. It also describes the pin connections for a shorting plug and null modem cable.


The MTEST program is supplied with C source code and shows how to transmit and receive data using the Kernel Stream driver. It shows the OEM developer an example interface and can be used to build custom applications. Minimum of one board with a test plug is needed or it can also be used with two boards connected back to back.

msend.exe AND mreceive.exe
These programs demonstrate how to use the Kernel Driver to transmit and receive in a half duplex mode. Because it is half-duplex there is a separate send side and a receive side program. Together they demonstrate a software interface to the Kernel Stream driver which can be used as a starting point for OEM application software. Source code is supplied.


Two systems are needed in order to properly test the drivers; a transmit computer and a receive computer, connected back to back with a null modem cable. Each computer must have a WAN/T1 Master installed. The transmit and receiving computers can use one of a range of available interface modules. The two computers must be connected using the proper null modem cable. Null modem cables are available for all of the modules listed in the following table.

Module Description
IM232-DTE RS-232 Interface
IMV35-DTE V.35 Interface
IM530/449/422-DTE EIA-530 or RS-449 or RS422 Interface
IMX.21-DTE X.21 Interface
IM-HSSI High Speed Serial Interface (HSSI)
IM-T1-CSU T1 CSU/DSU interface

The Kernel Driver can be used to transmit information from point to point or point to multi-point. It can also be used in both full duplex and half duplex applications. A satellite modem example is shown below.




*Note that the Forge/Fusion can be substituted if higher quality video is needed. Data rates up to 13.5 Mbits/sec are possible using the IM530/449-DTE-100 module.