User Manual

10 Command Summary
Power Through DB9 Jumper
In order to provide power through pin 9 of the DB-9 Connector you must connect the Power Through
DB-9 Jumper labelled R82, as illustrated below. This connection can be made using a zero ohm resistor,
recommended size 0603, or a solder bridge. The GLK240128-25/GLT240128 allows all voltage models to
use the power through DB-9 option, see the Voltage Specifications for power requirements.
Figure 9: Power Through DB9 Jumper
Protocol Select Jumpers
The Protocol Select Jumpers provide the means necessary to toggle the GLK240128-25/GLT240128
between RS-232, TTL and I²C protocols. As a default, the jumpers are set to RS-232 mode with solder
jumps on the RS232 jumpers. In order to place the display module in I²C mode you must first remove
the solder jumps from the RS232 jumpers and then place them on the I
2
C jumpers. The display will now
be in I²C mode and have a default slave address of 80, unless changed with the appropriate command.
Similarly, in order to change the display to TTL mode, simply remove the zero ohm resistors from the
RS232 or I²C jumpers and solder them to the TTL jumpers.
Hardware Lock
The Hardware Lock allows fonts, bitmaps, and settings to be saved, unaltered by any commands. By
connecting the two pads near the memory chip, designated R60, with a zero ohm resistor, the display
will be locked. This supersedes the data lock command and cannot be circumvented by any software
means. To unlock the display and make changes simply remove the jumper.