Installation Guide

SAFEmine Ltd | www.safe-mine.com | [e-mail] 35/39
SAFEmine (part of Hexagon Mining)
Baarerstrasse 133, CH-6300 Zug
Switzerland
www.hexagon.com
4.5. GPIO Connections
The CAS system offers to interact with its environment through eight general purpose input/output
ports. The outputs may drive (source or sink) 400mA each and at the same time. The inputs are
designed to work on switches, providing either pull-up or pull-down configurations.
Due to the multi-purpose nature of the CAS GPIO input/outputs it is not possible to galvanically
isolate them. If galvanic isolation is required install a protection relay in the signal path.
Further, always connect inputs/outputs to non-sensible systems. Since the CAS system is
permanently powered, it must be made sure it can never feed current into a potentially dangerous
subsystem.
For example: Always connect the reverse gear sense line to the switch side, which connects to the
buzzer or the strobe for reversing. Never connect on the relay coil side or on a driving output!
It is compulsory to mount protection relays when the inner workings of signal sources are not
completely understood or the receiving subsystem might act unexpectedly.
The following schematic shows the recommended connection to the reverse switch signal in a
vehicle with negative isolation switch (as found in Caterpillar and alike).
This configuration prevents eventual currents flowing from the CAS reverse input to the vehicle
systems when the isolator switch is opened or the negative connection of the CAS should become
disconnected.
Protection
Relay
Isolator
Switch
SAFEmine CAS
Vehicle load
Reverse
Switch
Battery