Controlling a LED display with Max
We’ve got a LED display, Alpha 220C model, that we want to use for a dance show. The idea is to be able to send messages to the display at will, using MIDI sensors (buttons) or the like.
I’m wondering if anybody has experience in using that kind of setup. The display is attached via serial port to the computer.
Is it possible at all to send scripts via the serial port? Or do I look at a dead end?
Thanks for any answer,
Amaury Groc wrote:
> We’ve got a LED display, Alpha 220C model, that we want to use for a dance show. The idea is to be able to send messages to the display at will, using MIDI sensors (buttons) or the like.
> I’m wondering if anybody has experience in using that kind of setup. The display is attached via serial port to the computer.
> Is it possible at all to send scripts via the serial port? Or do I look at a dead end?
basically it is possible to send your own text messages to the display
if it connects to the serial port. However, depending on the complexity
of the data format the display wants to see it could get quite
complicated to generate the data within ‘native’ Max.
I recently wrote an external for a similar display made by Genesis
Photonics because the data protocol required to send checksums that
would have been really complicated to calculate in Max.
So, yes, it can be done, but the complexity of the task depens on the
complexity of the data protocol.
Thanks a lot, Olaf, for that answer.
At least I know that is possible. My prolem is that I have no idea about how to write an external adapted to my device. I have the data protocol sheet, it is connected via serial port, and I’m using Max/msp 5.4 PC version.
Is the external written in a programming language, such as C++ or the like?
there is an application for that display that allows to write xml files for developers to integrate into an application. I just don’t know how to write that application.
If you can give some clue, not a programming lesson, but of the method, language and how it is working in Max, I’d be very thankfull. I at least need an overvew to se if I can hire someone or ask someone to help on that matter.
We’re having a creation in a national theater here in Paris and need this tool to work as soon as possible.
Thanks again for the help,
Amaury Groc wrote:
> At least I know that is possible. My prolem is that I have no idea
> about how to write an external adapted to my device. I have the data
> protocol sheet, it is connected via serial port, and I’m using
> Max/msp 5.4 PC version.
You don’t need to write an external, it exists already, called serial
and is standard as I recall…
The protocoll is all you need…
I started figuring out yesterday. I could finally communicate using the serial object. Since I’m so unfamiliar with these protocol and did not have an idea what the display was expecting, I sort of hacked a message a ready made application was sending to it, to analyze it and then to resend it to the device in the right format.
I’ll keep studying that today, hopefully will come with an elegant solution of generating the decimal messages from strings and attributes I need.
I’m trying the exact same with a similar Velleman display. I have no clue what the display expects me to send through the serial object.
How did you work it out?
And how did you hack that readymade program?
Well, it’s been laborious to say the least.. I tried to make out using the data sheet from the LED display I was using, and since I don’t really understand this stuff, it was a lot of trial and error to find out what was what, like, this bit determines colour, this one the font type, these ones the text.. Basically, the message to send to the display is a list of numbers..
I also got some help from someone on this board, that helped me to at least have confidence :), and more, to be sure my display did not need a ‘checksum’ message, so that I had less programming to do.
This is not of great help, but that is how it worked for me… Get the data sheet from your display, that describes the kind of message the display waits for, and try!
I actually got the protocol from the guys at Velleman.
Would you be so kind to take a real short look at it?
I have a feeling it might be very similar to yours…
Again, I almost understand nothing to that stuff.. So I can’t be of great help. I can only give my (very cumbersome) method: I ‘listened’ to one of the messages that the provided software was sending to the display, and found out what was what with trial and error (changing the numbers in the message), coupled with a comparison with what I could get from the protocol.
One thing that helped, and another user had told me about, is that my disply did not need a checksum message. That made it easier. I don’t know about yours..
Sorry again, I would love to help more, but I’m sure someone could be better at that!
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