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Several pre-purchase q's on usage of MX401 or simular

Posted: Tue Mar 14, 2006 5:45 pm
by philg
Hi, I have been thinking of making an external LCD display unit for a server I have in a cupboard. I want a display + keypad which I can use to control the server from another room.

Whilst I'm at it, I would like to be able to put several temperature sensors around the place, and be able to read the temps on the PC (and display on the LCD) It seems that I can use the I2C bus inputs to put lots of temperature sensors on this thing?

Also, I would like to be able to control other devices from the keypad on the LCD (for example I want to be able to send an on/off pulse to another device (5v high for on, 0 for off - actually to feed into a relay driver circuit I have built).

Can I use say a MX401 for this? I would also really like to be able to reset my PC using the keybad - is this possible with or without software support on the PC (ie if the PC locks up, can I reset it?)

I see the MX401 has GPO's I presume this means general purpose outputs... Can these be controlled directly from the attached keypad or do they require software on the PC to intercept the keypress, then controll the GPO?

Is there any real difference between the serial and usb models other than the interface - I guess I would prefer USB - but I use Windows XP x64 - are there drivers to support this - if not I can use the serial i/f with USB-Serial converts that I already make use of (I've run out of onboard COM ports already!!)

The other question, I see the mountings are generally for PC drive bays. I would want to mount this in an external box - is this possible (to mod the montings provided - or to use the template thing to create my own faceplate for the box?)

Finally, do you ship to the UK - I see there is a uk distributor but they dont seem to stock any MX4xx's which I think is what i want (4x20 line display at least).

Sorry for the masses of questions.
Thanks in advance for any feedback.

Posted: Thu May 04, 2006 12:45 pm
by Jon
Hi sorry for the long delay in replying to your query. I just noticed that your questions hadn't been fielded yet and I'd like to apologize for that. I think it has been tough for anybody to answer your question because it is a little bit more complicated than it seems. This is because if you use your computer as a controller for the LCD, as soon as your computer stops responding, your display will stop responding.

So I'll try to break it down into the parts that you discussed:

1. Temperature Probes - Both the MX4's and 3's feature 1-wire headers which can address up to thirty-two 1-wire devices on a single bus. This would allow you to build a 1-wire bus and link your temperature probes together and place them in different locations around your server room.

2. Controlling a Relay - This can be done using one of three GPOs on the MX414. The GPOs, or general purpose outputs, can provide up to 5V 20 mA of current, which would be suitable for providing on and off pulses to your relay. The one note that I will have to make about controlling relays is that you'll want to ensure that you clamp the relay with a diode and capcitor in order to absorb any EMF.

3. Turning off the PC - This will require a little bit of experimentation, I'll be happy to help anybody with the details that wants to give it a try. Basically you'll have to have a controller monitoring the tx line on MX for keypresses and have the same controller board connected to the pwr switch on your ATX power supply. When the controller notices that the particular key has been pressed it will cause the powersupply to be turned on or off.

4. Serial & USB - The main difference is that the USB units have 4 advanced GPO's which output 12V 1A and 3 regular GPOs (5V 20mA), and the serial units only have the regular GPOs. Also another difference is that serial units do not come as a package, ie. the LK204-24-USB can be purchased as an MX4XX which comes with the 15button keypad USB cable and software CD with LCDC key. For the LK204-25 (Serial) you must purchase all of the components seperatly.

5. Mounting - please email nick at and he will send you a list of enclosure companies that can build you a custom enclosure.

6. UK distributor - Kustom PCs

Posted: Thu May 04, 2006 12:58 pm
by philg
Thanks Jon,

As you can imagine with such a delay, I went ahead and got myself a MX401 from one of your UK distributers.

I've mounted it in a standard black ABS plastic box, on the wall in my hall. It all works - although Im using a customised version of LCSSmartie to control the display (I added the funcitons to read the temperature sensors - and log them to a file at the same time)...

All seems to be working well...


Turning your computer on/off

Posted: Thu May 04, 2006 1:30 pm
by Jon
Well I'm glad that you went ahead and purchased the display and everything is working well.

Have you decided to work on getting the display to turn the comptuer on and off?

Posted: Fri May 05, 2006 2:59 pm
by philg

I dont think its going to be practical to turn on/off the computer... Firstly, I would only want to reset it really (its a server in a difficult to reach place)..

The only time I would want to do that, is if it has crashed... And if it has crashed, then there is not going to be any control/response from the LCD software.

So no, I havnt tried it, and I dont think I will be trying it... But everything else is working well -and doing what I want...

Im logging the temp sensors to a file, which mean sI can use software like MRTG to graph the temperatures around the room.

For example:

Ive hooked up 6 sensors so far - and have reached the maximum I2C bus lenght I think - so thats it for the moment!!