User`s guide

Infrared (IR) Port 41
E-EQ-MX1RG-D MX1 Reference Guide
Infrared (IR) Port
Figure 2-7 Infrared Port - COM2 Port
At the bottom, front of the MX1 computer there is an Infrared (IR) Data Port. The IR Port is
designed to provide a data link between the MX1 and a similarly equipped piece of equipment
such as a printer. The IR port is the MX1’s COM2 port and is a bi-directional half-duplex
communication port. It supports baud rates up to 115k (although restricted if using IrDA software
to 19.2k baud).
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. When sending data through the IR port while the MX1 is docked,
make sure the IR port on the docking station and the IR port on the second MX1 are in close
proximity to each other.
IrDA software is NOT installed or maintained by LXE.
IR Communication Reliability
Transmitted data is sometimes reflected into the receiver and the software programmer needs to
make sure the data is cleared before the IR port starts it’s receive routines.
When the MX1 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 MX1. 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”.