Does anybody has an idea how to make simple “pick to light” system.
Pick to light system is usually used in warehouse. This system makes very easy to find the product in the big warehouse that need to be shipped
When bar code is scanned on the computer computer communicates through some wiring and only lights on LEDs by the products that need to be picked up.
The best scenario is to use LEDs to display qty of the product that need to be picked.
Software is the easy part. What is the best way to connect tens or even hundreds of LEDs to a single computer. And what is the best components to use to make sure that only particular LEDs are turning on (is there a way to assign some serial number to each LED?).
Thank you very much for your response. All ideas are appreciated.
I’d say one main controller pic chip that scans in the bar codes and figures out the correct section and quantity to light up. Use USART out to send the data to another chip which receives the data in a format similar to this:
“S34Q2”
Which would indicate section 34, for a quantity of 2. You could send commands like this to signify turning on the specific lights. You could also send Q0 to signify turning off the lights.
The next controller that is receiving the USART data then needs to multiplex this data and map the output to the correct section and simply send that section the Q number. Once the section (just another pic would be simplest) receives a Q command via USART or serial or any other method, it responses by toggling its LEDs.
The main part is going to be the second controller responsible for multiplexing.
You used the term “big warehouse”. I assume that means thousands (if not 10s of thousands) of square feet. You mention 100s of products. Based on that I see 3 components of your system: main controller, network and multiple lighting units.
I would not recommend async (USART to RS232) for your network. It can’t go that far. Instead, I’d look at rs485 which can go much farther and is far more immune to noise.
You will need multiple lighting units. They need to be addressable. Each LU could support an area 10’ x 10’ or so, depending on how many lights you will need. each should have an rs485 transceiver, processor and light drivers. It could also have a display to give product number but that might raise the cost too much. Each unit will have a unique address and your main controller is responsible for mapping location to LU and LED. You can drive an almost unlimited number of LEDs using shift registers though I wonder how effective LEDs will be in your large warehouse. I would make the LUs pretty dumb - just take commands to light a specific LED.
Alternatively, you could use ethernet or Wifi but that’s going to raise cost. If you’ve got the budget for it, I’d consider that. Then you just use a standard PC as your controller. Integration with your inventory system will be easier.
I used to work for one of the major suppliers and installers of pick and put light systems. Naturally I can’t elaborate on the details of the system, but will say that Philba is very close with his architecture overview and communication methods.
The one thing I will add: make sure that the individual lights are very strong, easily replaceable, and have reliable connectors. They WILL fail. Try not to have a complicated system for assigning a particular replacement light to a location.
It’s just a matter of choosing the viewing angle and number of LEDs. You can get indicator buttons intended for industrial use that have a cluster of LEDs and are set up to run on handy voltages like 24V. Warehouse lighting can actually be pretty dim sometimes…often pick systems are under conveyors and other equipment or storage racks, and the metal halide lamps are pretty far up there and not always spaced very closely. In one system I used a single red/green diffused 5mm LED for a wireless signal strength indicator; you could easily tell what the status was from the other end of the 525-foot system.
Thank you very much. RS-485 should work. Because it’s cheap easy to work with and it’ll work on bigger distance (in the large warehouse). LED will be visible because “pickers” will be only few feet away (each picker assigned to his zone up to 20 feet).
Could you please give me a link to an article or an idea how I can make LU (lighting unit). What parts do I need?
I am good with software but I know very little about hardware part. And I appreciate all your help. Now at least I know where to start.
A housing. Plastic will work just fine, look at Bud Industries. PolyCase or New Age Enclosures for lots of options which can be customized for a low cost (either by them or an outside shop)
Lighting thing. Fire up Digikey and see what types of indicator diffusers or similar items you can find. I wouldn’t use RAW leds poking out of a box (fragile, directional).
Pick a microcontroller platform. As you’re going to use a asynchronous serial bus, you’ll be best off with a real U(S)ART peripheral. I suggest a low cost AVR, such as a Mega88 (you really won’t need much program space and want to keep cost low). There are cheaper options (Freescale HCS08 QB series), but not as big of a development community on the public internet.
You will need to use a real crystal (not the internal oscillator on the AVR) for maximum reliability.
An RS485 driver chip. TI has many options which are easy to use.
A connector and cable standard. Something robust and positive latching is my recommendation. There are 100001 options out there (and none do what you want, and if they do, cost far too much).
Some LEDs (to light up the diffuser/indicator).
A voltage regulator per lighting board - I would suggest sending 24V down the bus cable, which will need to be converted to 3.3 or 5V at each LU.
A method of switching the LEDs on/off (N-channel MOSFET), if several are in series on the 24V power line.