AFDAU-T1 Aerial Firefighting
Data Acquisition Unit
Installation Manual
AMS-IM-1-01 Rev. 7
22 September 2021
19
Relay Connection Pinouts
Main Connector (J1) Relay Pins
Description
K1
K2
K3
K4
K5
K6
32
33
34
35
36
37
+28Vdc Input
14
15
16
17
18
19
Ground
CAUTION
CARE MUST BE TAKEN TO ENSURE THAT WHEN A RELAY IS CONNECTED IN PARALLEL
TO AN EXISTING CIRCUIT THAT IT IN NO WAY INTERFERES WITH THAT CIRCUIT.
NOTE
A common problem amongst some tracking hardware manufacturers when wiring up a
discrete input to a warning light circuit is that a high voltage (14/28VDC) represents an OFF
condition. I.e. MGB Oil Pressure light is ON therefore meaning the engine is OFF. During
power on this voltage raises from LOW (0 vdc) to HIGH (14/28 vdc) voltage and is falsely
detected as an Engine OFF event. The AFDAU does not suffer this issue and handles this
problem through its firmware, no additional circuitry such as additional relays are
required, using an internal relay provided in the AFDAU is sufficient.
