IrDA Lite Plus 97
E-EQ-MX3RG-J-ARC MX3 Reference Guide
IrDA Lite Plus
Note: IrDA Lite Plus is not compatible with LXE's terminal emulation programs.
IrDA Lite Plus (IRPLUS.EXE) is a DOS device driver that complies with the standard produced
by InfraRed Data Associates for infrared communications.
The IrDA Lite Plus device driver was developed for the LXE MX3 computer. It is a standard
DOS device driver which converts data sent to the LPT/PRN, and COM1 and COM2 ports via the
BIOS, DOS, and a proprietary application interface to infrared data that is transmitted using the
infrared port on the mobile computer. Even though this device driver was developed for the MX3,
it works on a regular PC with an installed infrared port or an attached serial to infrared converter
cable (commercially available).
Note: The MX3’s IR Port is COM2 regardless of the endcap installed on the MX3.
On the back of the MX3 Computer is the InfraRed (IR) Data Port. The IR Port is designed to
provide a data link between the MX3 and a similarly equipped piece of equipment such as a
printer.
The IR operating envelope has a distance range of 2 cm (.79 inches) to 1 meter (3.2 feet) with a
viewing angle of 30 degrees.
Operation of the IR Port is application dependent so a description of implementation varies from
application to application.
System Setup
When preparing to use IrDA Lite Plus, a command line must be added to the CONFIG.SYS file in
the MX3. See the “Quick Start” section that follows.
The IrDA Lite Plus file must be loaded on each MX3 and/or PC used in the file transfer.
When using a PC that does not have an installed IR port, a commercially available serial to
infrared adapter is required for IR file transfer to/from the MX3.
IR Communication Reliability
Transmitted data is reflected into the receiver and the software programmer needs to make sure
the data is cleared before the IR port starts its receive routines.
When the MX3 is transmitting data to the PC, it starts to fill up its Tx FIFO buffer (First In First
Out). During transmission, any reflections or light disturbances from the IR medium are going to
get interpreted as data and is clocked into the Rx FIFO buffer. Unless software developers take
preventative steps, when it goes to access the Rx FIFO buffer to determine if an ACK was
received, it may find data and “thinks” it did not receive an ACK because it contains corrupted
data due to the reflections or disturbances coming in from the IR medium. Software must be able
to handle these types of reflections or disturbances at any time during transmit or receive when
using IR communications on the MX3. If the receive algorithm requires that a specific character
be present in a specific sequence, extra precautions/steps must be taken to properly manipulate the
receive sections of the system. For example, if the software expects the first character received
after a transmission to be an “ACK”, the software design must be such that the receive buffers and
shift registers are cleared first of any other characters before getting the “ACK”.
