Control a LED panel over Ethernet TCP/IP

[Oliver Ekeis]

Hi NG,

I hope I'm not OT here. If I am, please let me know.

I want to design the following: I've written a special
software to control a lot of measured data. If the
measured data drops down and falls below a selected level
a warning must come up. I do so within the software. But
in addition there must be an LED panel which shows the
alarm status via a (blinking) red LED. The panel is far
away from my computer. So I had the idea to address it
via the local network.

My question is: Does anybody have an idea to address
about 250 LED warning lights via ethernet (TCP/IP socket)
not using a PLC? Maybe a little electronic circuit with
a TCP/IP controller chip (which receives a command that
sets a specific 8-bit pattern) and a chip that interprets
the incoming bit pattern and sets 256 digital outputs.
This circuit must be cheap and should be set up by a
non-electrician-engineer ;-)

Thanks for your advice.

Oliver.

 

[Tim Wescott]

Oliver Ekeis wrote:

Hi NG,

I hope I'm not OT here. If I am, please let me know.

I want to design the following: I've written a special
software to control a lot of measured data. If the
measured data drops down and falls below a selected level
a warning must come up. I do so within the software. But
in addition there must be an LED panel which shows the
alarm status via a (blinking) red LED. The panel is far
away from my computer. So I had the idea to address it
via the local network.

My question is: Does anybody have an idea to address
about 250 LED warning lights via ethernet (TCP/IP socket)
not using a PLC? Maybe a little electronic circuit with
a TCP/IP controller chip (which receives a command that
sets a specific 8-bit pattern) and a chip that interprets
the incoming bit pattern and sets 256 digital outputs.
This circuit must be cheap and should be set up by a
non-electrician-engineer ;-)

Thanks for your advice.

Oliver.

If you want to do just one a PLC may be cheapest. Alternately, a PC-104
stack with a processor, digital I/O board, and a bunch of software would
work. The nice thing about the PC-104 solution is that you already know
your way around a PC.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

 

[Ian Stirling]

Oliver Ekeis <ekeis98@gmx.de> wrote:

Hi NG,

I hope I'm not OT here. If I am, please let me know.

I want to design the following: I've written a special
software to control a lot of measured data. If the
measured data drops down and falls below a selected level
a warning must come up. I do so within the software. But
in addition there must be an LED panel which shows the
alarm status via a (blinking) red LED. The panel is far
away from my computer. So I had the idea to address it
via the local network.

My question is: Does anybody have an idea to address
about 250 LED warning lights via ethernet (TCP/IP socket)

You can get ethernet-serial converters.
There are several on ebay at the moment.
Then the problem reduces to doing serial-LED.

 

[hamilton]

Tim Wescott wrote:

If you want to do just one a PLC may be cheapest.

Tim, what is the cheapest PLC I can buy off the shelf ???

hamilton

 

[Joerg]

Hello Oliver,

Yet another idea would be to use an old laptop at the remote location. If this is a one-up project in a company you are probably retiring many laptops per year, most of which will have a built-in network card. That way your technicians don't have to mess with the LAN setup, especially if you are using DHCP already.

Since older PCs still have a parallel port the addressing of the LEDs should become pretty trivial.

Regards, Joerg

http://www.analogconsultants.com

 

[Oliver Ekeis]

Hi Matt,

thanks a lot. This was a great proposal. Looking at your LED
matrix there is one point I don't understand. Considering the
following example: You want to light the LEDs V1, V6, VB
and VG. It is the diagonal from the top left to the bottom right.
In this case you'd have to connect the contacts W, X, Y and Z
to +V and the contacts 1, 2, 3 and 4 to ground at the same time.
But if you do so, all LED will flash. The problem is, you cannot
control a set of LEDs (a special pattern) in a unique way.

Do you have any idea how to cope with that?

Please note: the LEDs should signalize some status and they
must be controlled independent. A single LED must be switched
on and a set of LEDs must be switched on independently.

Thanks for your help.

Oliver.

 

Oliver Ekeis <ekeis98@gmx.de> wrote:

Looking at your LED matrix there is one point I don't understand.
Considering the following example: You want to light the LEDs V1,
V6, VB and VG. It is the diagonal from the top left to the bottom
right. In this case you'd have to connect the contacts W, X, Y
and Z to +V and the contacts 1, 2, 3 and 4 to ground at the same
time. But if you do so, all LED will flash. The problem is, you
cannot control a set of LEDs (a special pattern) in a unique way.

What you do is to only connect one of the W, X, Y, Z lines to +V
at once, and only one of the 1, 2, 3, 4 lines to ground at once.
The LEDs that are lit are not on for 100% of the time. If you
do this fast enough, your eye perceives an LED that is lit all
of the time.

The lights in your house work this way. They are actually flashing
off and on 100 times a second, but this is so fast that you see a
steady light. Most LED clocks have this kind of display; try eating
some crunchy food while looking at an LED clock and you will see
the digits shimmer and move around, because your eye is in a different
position each time the LED is lit for a fraction of a second.

To display the LEDs 1, 6, B, and G with the matrix I used, the
logic might go like this:

1. Connect W to +V.
2. Do I want to turn on 1? Yes! Connect 1 to ground. LED 1 turns on.
3. Disconnect 1 from ground. LED 1 turns off.
4. Do I want to turn on 2? No. Continue.
5. Do I want to turn on 3? No. Continue.
6. Do I want to turn on 4? No. Continue.
7. Disconnect W from +V.

8. Connect X to +V.
9. Do I want to turn on 5? No. Continue.
10. Do I want to turn on 6? Yes! Connect 2 to ground. LED 6 turns on.
11. Disconnect 2 from ground. LED 6 turns off.
12. Do I want to turn on 7? No. Continue.
13. Do I want to turn on 8? No. Continue.
14. Disconnect X from +V.

15. Connect Y to +V.
16. Do I want to turn on 9? No. Continue.
17. Do I want to turn on A? No. Continue.
17. Do I want to turn on B? Yes! Connect 3 to ground. LED B turns on.
18. Disconnect 3 from ground. LED B turns off.
20. Do I want to turn on D? No. Continue.
21. Disconnect Y from +V.

22. Connect Z to +V.
23. Do I want to turn on C? No. Continue.
24. Do I want to turn on D? No. Continue.
25. Do I want to turn on E? No. Continue.
26. Do I want to turn on F? Yes! Connect 4 to ground. LED F turns on.
27. Disconnect 4 from ground. LED F turns off.
28. Disconnect Y from +V.

29. Go back to step 1.

Matt Roberds