Hemisphere GPS MBX-4, User Manual

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2: Installation
RS-232 and RS-422 Operation
A majority of GPS receiver products communicates at the RS-232 level,
similar to a PC computer. However, there are a number of chart-plotting
devices, incorporating GPS capabilities, that operating at the RS-422
interface level. The default communication level of the MBX-4 is RS-232.
To switch from the default RS-232 communication level, you must
remove the MBX-4’s front and back panels to slide the receiver board
out of the case approximately 2 inches (5 centimeters). Always observe
proper electrostatic discharge precautions (ESD) when handling the
beacon receiver or its components, outside of the enclosure. Such
precautions include proper grounding of personnel, tools, and the
surface upon which the receiver rests.
You will require a Philip’s screwdriver to open the front and back panels
of the MBX-4. Once you have removed the front panel screws for the
MBX-4, carefully remove the front plate and disconnect the ribbon
cables of the display and keypad, taking note of connector orientation
when secured. Do not pull on the ribbon cables, hold onto the
connector when removing so that strain is not placed on the cable.
When making this modification, do not draw the printed circuit board
fully out of the enclosure. Instead, slide the board out no more than two
inches before reaching in to reposition the RS-232/RS-422 slide switch.
Use of a ball-point pen is recommended when making this adjustment.
Figure 2-4 illustrates the location of the RS-232/RS-422 slide switch
within the receiver: