Constructing a URL


Pick to Light example device



Our Pick-to-Light system uses the ultimate standard – a simple web URL.

A simple URL request, sent to our server on the Amazon Cloud, causes the associated Pick-to-Light device to light up with any two lines of custom text. Now, you can use pick-to-light in new ways!

Integration is so simple that you can even use it with Excel or Google Sheets.

If you need more flexibility, check out our REST API.

voodoo robotics stacked logo


Secure Protocol

HTTPS (Hyper Text Transfer Protocol Secure) is the secure protocol over which data is sent over the internet.  Using this protocol, as opposed to HTTP, ensures that your communication is encrypted.  It is often used for highly confidential transactions like online banking or shopping. Voodoo Robotics’ API requires the use of this secure protocol.


Our Server

We use Amazon’s AWS cloud services to provide a secure state-of-the-art environment that is flexible, reliable, scalable and secure.  By specifying our server name,, you’ll connect to one of many redundant servers waiting to process your request. Since you’re not requesting a normal web page, but instead using the API, add the ‘api’ parameter.


Device ID

Each wireless device has a unique identifier. That’s right–every single device is unique and directly addressable. The 12 digit hexadecimal number is in the form D4F660:AFA0CB.  Press the button on any device to get its ID.


Type of Command

There are four commands you can send to a device to display or store data:

  • ‘flash’ or ‘message’

    The most common command is the ‘flash’ command which causes the button to light up flashing, and the device to display up to five lines of text or an encoded icon, barcode or QR-Code.  Using the word ‘message’ does the same thing.  (It’s an alias.)

  • ‘pick’ or ‘display’

    Similar to the ‘flash’ command, the ‘pick’ command causes the device to light up, but this time with a continuous button light, along with the display of up to five lines.  The word ‘display’ is an alias of ‘pick’–they do the same thing.

  • Note!

    Prior to device firmware 57, a ‘flash’ or ‘pick’ (or ‘message’ or ‘display’) command overwrote any previous command pending on a device.  In order to support multiple commands at the same time, firmware 57 modified this behavior.  Now in order to remove or overwrite any previous commands, you should send a ‘reset’ command.

  • ‘static’

    The “static” command stores up to five lines of text in the device display.  For example, you can store the color or size of the inventory stored at this location.  Or you can attach a device to a forklift and display maintenance information on it.  That way an operator can check the equipment status at a glance.

    Use your imagination! There are so many useful things you can display on these devices.

    You can also use the word “background” instead of “static”.

    * You can also set this parameter by editing Device settings on the SKU-Keeper website.

  • ‘location’

    The ‘location’ option overrides the location information stored on the device as maintained on the SKU-Keeper website.

    * You can also set this parameter by editing Device settings on the SKU-Keeper website.


Display Lines (up to five)

Devices can light up with up to five lines of custom alphanumeric (Western style) text.  The devices can display 26 characters across in each lines of text.  Instead of a line of text, you can encode an icon, a barcode, a QR-Code or all three!  (Note that two fields are used to preserve backward compatibility with our Classic devices.  You can leave one blank and put all lines in the other, if you’d like.)



Devices can play a custom tune when the button lights up. Here are some examples:

Regular Beep 15,c5,4
Macaroon 250,c5,1,e5,1,g5,1,c6,1,g5,1,e5,1,c5,1
Marshmallow 200,d5,3,d5,1,f5,2,f5,1,g5,1,f5,2
Meringue 250,c6,1,a5,1,b5,1,g5,1,f5,1
Milkshake 300,a5,1,g5s,1,f5s,1,d5,1
Mousse 160,e5,3,e5,1,g5s,2,b5,2,a5,2
Muffin 250,a5,1,c6,1,e6,1,c6,1,e6,1,c6,1,e6,1,c6,1,a5,1
Charge 140,c5,2,f5,2,a5,2,c6,3,a5,1,c6,3
Charge2 140,c5,2,f5,2,a5,2,g5,2,e5,2,f5,2,g5,2
Twilight 140,g5s,2,a5,2,g5s,2,e5,2,g5s,2,a5,2,g5s,2,e5,2
Waterfall 140,a5s,2,g5s,2,f5s,2,d5s,2,c5s,2,d5s,2,f5s,2
Skip Along 140,f5,2,f5,2,d5,2,f5,2,e5,2,d5,2,c5,2
Yankee Doodle 140,f5,2,f5,2,g5,2,a5,2,f5,2,a5,2,g5,2
Scale 140,c5,2,d5,2,e5,2,f5,2,g5,2,f5,2,e5,2,d5,2,c5,2
Scale–Reverse 140,c6,2,b5,2,a5,2,g5,2,f5,2,g5,2,a5,2,b5,2,c6,2
Day is Done 140,c5,1,c5,1,f5,3,p,2,c5,1,f5,1,a5,3
Ta-Da 140,e5,1,e5,3,g5,1,g5,3,c5,1,c5,3
Dreidel-Dreidel 200,g5,1,c6,1,c6,1,d6,1,d6,1,e6,1,c6,2,e6,1,g6,1,g6,1,f6,1,e6,1,d6,3,a5,1,


Sakura 200,a6,2,a6,2,b6,4,a6,2,a6,2,b6,4,a6,2,b6,2,c7,2,b6,2,a6,2,b6,1,a6,1,f6,4,




Constant 15,c5,400

The waterfall example above, starts with ‘140’, a value that represents the tempo.  Then ‘a5s’ is the note A sharp in the fifth octave, held for ‘2’ beats.  Separate notes by commas.  Use ‘p’ for a pause.  You get the idea!

* This part of the URL is only needed for a ‘pick’ or ‘flash’ command!


Seconds and Color

This URL section specifies how long, in seconds, the device should light-up.  If you want a device to stay lit until the button is pressed, use a value of ‘0’.  But do you really want to do that?  You might use up the batteries in a device if the button is not pressed.

The suffix can be an ‘r’ for red, ‘g’ for green, ‘b’ for blue, or any combination of two of these.

* This part of the URL is only needed for a ‘pick’ or ‘flash’ command!


Acknowledgement Nonce

For users that need pick confirmations with Modern devices, we recommend encoding a barcode or QR-Code to be scanned by the picker for that purpose.

For backward compatibility reasons, we still support this optional last parameter that the user can add to their URL.  It as a transaction ID to identify a particular call to the device.  It can be a random number, or it could be a counter, or it could be a nonce.  It’s up to the user to choose.

Learn more about how to create a closed-loop system.

* This part of the URL is only needed for a ‘pick’ or ‘flash’ command!

© Copyright 2021 Voodoo Robotics. All Rights Reserved. Patents Pending. Voodoo Robotics, SKU-Keeper, SKU-Turbo, and SKU-Station logos are all trademarks of Voodoo Robotics.