Matrix Orbital LCD/VFD Legacy User Manual
Page 3
DB-9 Connector Pin Out
RS-232 port: This connector is wired so that a standard “straight through” 9 pin D-sub cable may be used to connect the
modules on a standard serial port such as comm ports on PCs. Note that this device complies to the EIA232 standard in
that it uses signal levels from +/- 3V to +/- 12V. It will not operate correctly at TTL (0 to +5V) levels.
Note: Signals are shown as interpreted by the Liquid Crystal Display module.
Power may be provided to the module by pin 9 of the DB-9 connector instead of through the 4-pin SIP. If power is to be
applied using the DB-9, it must be a regulated +5Vdc supply. If the user intends to use pin 9 as the power source, the user
must solder the 5 volt jumper point beside the DB-9 connector. If you have any further questions or concerns please don’t
hesitate to contact Matrix Orbital.
W
ARNING
: U
SE
THIS
METHOD
OF
POWER
UP
AT
YOUR
OWN
RISK
. A
PPLICATION
OF
A
VOLTAGE
TO
PIN
9
GREATER
THAN
5.5
VOLTS
WILL
CAUSE
IMMEDIATE
DESTRUCTION
OF
UNIT
AND
VOID
THE
WARRANTY
.
Note: This applies to wide voltage units (V extensions) as well as to standard 5 volt units.
General Purpose Output (GPO)
The GPO is meant to be used as a pair. The positive side of the GPO is connected to a power source of +5Vdc supplied by
the module at 20mA. The negative side of the GPO is capable of finding a path to ground through a 240 ohm resistor. This
resistor will limit the current flow through a GPO to approximately 20mA in the event of a short circuit. If the device
which is being driven by a GPO requires a relatively high current (such as a relay) and has an internal resistance of it’s own
greater than 250 ohms, then the 240 ohm resistor may be shorted. You will find this resistor directly below the negative pin
of the general purpose output.
Note: This operation requires soldering. The GPO does not have any over current or over/under voltage protection so care
must be taken if the user decides to connect the negative side differently. For instance if the external device is a relay it must
be fully clamped to absorb any generated back electromotive force (EMF).
3
Pin Number
Description
2
Data Out
3
Data In
5
Ground
9
+5Vdc