Power outputs

The Edge Controller V2 has 8 controllable power outputs. These can be used to power accessories such as cameras, speakers, floodlights, strobelights etc. They can also be used to trigger relays or other low power signals.

The 8 power outputs are highlighted red above.

Features

• Switching currents up to 7A per output @ 12V nominal

• Capable of parallel operation for 10A+

• Adjustable 'efuse' setting from 1A to 7A

• Soft start to avoid large inrush currents

• Reverse current blocking

• Reverse polarity protected

• Short circuit protected

Configuration

In the device definition the following parameters can be configured

Minimum current level

If the output is switched on but the current flowing through the chip is less than this configured level, an error will be raised in the platform. This is useful to determine whether accessr

Maximum current level

This defines the maximum expected current level before the output will automatically shut down.

Note that this is not an instantaneous shutdown and the delay before shutdown is not guaranteed. It is designed to provide a warning that the system is wired incorrectly.

Wiring

Each output has a +12V pin and a ground pin. All of the ground pins are tied to a common negative with the power inputs.

The maximum capacity of each output is 7A.

Up to 2 outputs may be tied together for a combined maximum of around 12A. It is important that the outputs are linked with a low resistance wire and that the cable lengths are balanced.

We recommend using a minimum of 0.5mm2 thinwall (FLRY) cable with a current rating of at least 10 amps.

Fault indication

Each output has a green LED and an orange LED on the PCB.

The green LED indicates that the output is switched on.

The orange LED indicates that the output is in fault condition (and therefore disabled).

If you have both LEDs on that means the output is in fault condition and effectively switched off.

These indicators can also be seen in the Giraffe platform. In order to reset an output and clear the fault, it is necessary to switch it off and back on again. It will not try and reset itself.

Soft start

The outputs have a 'soft start' feature which gradually ramps up the power on the output to prevent a large current surge.

There is a limit to the amount of capacitance that the output can support before it trips out due to overload on startup. We have tried to accommodate all normal loads we would expect to see.

However, we have seen some devices such as cameras that have a very large amount of internal capacitance (presumably to try and work with bad power supplies).

If the output trips out during startup, there are a couple of things that you can do:

• split the load over multiple outputs (ie. have 1 camera per output rather than 2 cameras on 1 output).

• parallel two outputs together

• use a relay board or time delay relays to stagger the startup of devices.

We have also seen some situations where a device with a built in DC/DC converter (such as an LED floodlight) can switch on at very low voltage whilst the Edge Controller output is still ramping up. This result in a very large current draw that can trigger the over current protection.

The only real solution to this is to parallel two outputs or to stagger the startup of the floodlights.

Parallel operation

We recommend combining a maximum of 2 outputs to increase the maximum current output.

This will allow currents of 10A or more if required.

Any combination of outputs can be combined.

Device Definition

The 8 primary outputs are aliased as outputs 1-8.

For instance, to configure floodlights to use channel 1 on the PCB

'floodlights' => [
    'enabled' => true,
    'output_id' => 1, // this is channel 1 on the PCB
    'minimum_current' => 0.5, // raise an error if switched on and current < 2A
    'maximum_current' => 10, // raise an error and switch off if current > 4A
],

To configure a camera power output which parallels channel 7 & 8:

        'camera_power_0' => [
            'enabled' => true,
            'output_id' => 7, // this is channel 7
            'description' => 'Mast Power',
            'linked_output_ids' => [8], // this combines it with channel 8
            'minimum_current' => 0.5, // raise an error if switched on and current < 0.5A
            'maximum_current' => 10, // raise an error and switch off if current > 10A
        ],

There are a couple of other flags that can be used on outputs:

Output Inversion

'inverted' => true,

This flips the logic so 'off' is electrically treated as 'on' and vice versa. This is useful if you are controlling a relay with an output and you want the user interface to show 'off' when the output is actually on.

It doesn't make sense to use current monitoring with this option so we recommend setting the minimum current to 0A so it will not trigger.

Default State

'default_state' => 'off',

This will set the 'default' state in the UI when an Edge Controller is first initialised. The default for camera_power_x outputs is on, for all other outputs the default is off.

Remember that this flag only affects the initial power on. If you manually then change the state in the UI, it will be remembered on the next reboot.

For some features such as floodlights this feature isn't very useful, because actions such as opening the doors will trigger the floodlights anyway.