AFR200 Series, Product User Guide
This document is subject to change without notice.
Caution: None of GAC products are flight certified controls including this item
Copyright © 2010, Governors America Corp., All Rights Reserved
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PUG4144 D
8.3 System Interface Information
The following sections provide greater detail on the basic system wiring information for the AFR series controllers
and some additional detail not covered in previous sections.
8.3.1 System Power
The AFR should be wired through a switched (On / Off Switch) DC power source of 5 to 32VDC and circuit
protected with a 20 Amp fuse or circuit breaker.
8.3.2 Power Relay (2A) Low Side Output (LSO)
The AFR has the ability to control a power relay when the system is enabled and use this for controlled
shutdowns of the engine. The output of this relay is tied to the ignition coil outputs (if an ICM is installed), the
oxygen sensor heater circuits, and the fuel shut-off solenoid (if applicable). This allows the AFR to control the
air/fuel, ignition, and fuel shut-off solenoids in the event of a controlled shutdown due to a high-temperature, low
oil pressure, overspeed, or due to an emergency shutdown using SmartVU.
8.3.3 Speed Selection Inputs
The AFR has two inputs which in various combinations allow the user to select between the 3 fixed speed settings
or the variable speed setting. This is accomplished by tying the inputs to ground or leaving them open. The
variable speed setting requires an additional potentiometer which can be OEM supplied or purchased from GAC
using the information provided previously.
There is a potentiometer calibration within SmartVU that characterizes the selected potentiometer. The following
table details the speed selector input combinations and the associated settings.
Speed Selection Table
Desired Selection
Speed Select
Switch Input 1
Speed Select
Switch Input 2
Variable Speed
Open
Open
Fixed Speed Setting #1
Ground
Open
Fixed Speed Setting #2
Open
Ground
Fixed Speed Setting #3
Ground
Ground
None of these selections are required and that the default setting (both open) is variable speed. The variable
speed setpoint can be set identically (i.e. same RPM) to act as an additional (or primary) fixed speed setting.
8.3.4 Communications
Two communications ports are available on the AFR: RS232 / Modbus and CAN / J1939.
8.3.4.1 RS232 / Modbus
The RS232 inputs are used to configure the AFR using GAC’s SmartVU software. A DB9-F is the standard
mating connector for diagnostic information for GAC products.
8.3.4.2 CAN / J1939
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Data Output: The CAN output supports J1939 protocol for basic engine sensor information and
Diagnostic Trouble Codes (DTCs). For J1939 data readers, the current implementation provides engine
