Specifications

Chapter 30: GPI Port Reference 301
Chapter 30: GPI Port Reference
GPI Port Specifications
A 9-pin, female DB9 connector provides a total of 2 General Pur-
pose Interface (GPI) Inputs and 2 Outputs.
GPI Input Specifications
The specifications for the GPI input are as follows:
• Inputs are logic inputs with pull-ups. They may be driven by
logic outputs or contact closure to ground.
• Input signal range is 0 to 5.5V. The inputs are ESD protected.
• Input signaling uses standard TTL logic levels: 0.8V or less for
a logic low. 2.0V or greater for a logic high.
• Inputs are compatible with 5V TTL (e.g. 74LS series), 5V
CMOS (e.g. 74HC series), 3.3V CMOS (e.g. 74LVC series)
• Inputs provide an internal 5K ohm pull-up to +5V.
• All Inputs are referenced to the same internal ground, which is
connected to AC safety ground.
GPI Output Specifications
The specifications for the GPI output are as follows:
• Outputs are isolated, floating relay contacts (contact closure).
• Switched voltage is 200V max; 0.5A max.
• Switched voltage with respect to safety/chassis ground is
300V max.
GPI Output Ground Connections
The GPI Outputs provided are isolated contact-closure style.
Each GPI output is presented on a pair of pins. These two pins
represent the two sides of a switch that can be opened and closed.
If it is desired to drive a signal to ground, then one of the pins
must be wired to ground, and the other to the signal to be con-
trolled.
GPI Connector Pin Assignments
The GPI port is a female DB9 connector that provides two GPI
inputs and two GPI outputs. The following table shows the input
and output pin assignments on the GPI connector:
Pinout for GPI Connector
GPI Outputs can switch 500 mA maximum. This applies even
to short term current surges. This limit can be exceeded when
driving a capacitive or incandescent lamp load. An incandes-
cent lamp may draw as much as ten times its steady state cur-
rent when first turned on. Therefore such lamps are typically
not appropriate loads for the GPI Outputs, and should in-
stead be controlled by a secondary relay.
DB9 GPI Connector Pin Assignments
Pin Number Function Comments
1 Input 1
Logic level (TTL, CMOS) input
with pullup
2 Input 2
Logic level (TTL, CMOS) input
with pullup
3, 8 Output 1
Floating contact closure out-
put
4, 9 Output 2
Floating contact closure out-
put
5, 6, 7 Ground
All ground pins are connected
internally
Pinout for the GPI port (looking at back of the E3 engine)
54321
9876