Control system design (temp control, cables, relays)

[MikeSv86]

Hello everyone.

For a project I need to design a temperature control system.
As Iam not an electrical or control engineer I only have an idea of how to solve that.

My biggest issue is how to implement the communication between Hardware and Software.
For some projects I used Labview and modules from National Instruments which works quite good.
Now I thought about controlling the temperatur system, which basically will be som heaters and Solid state relays, with labview an only an ethernet cable.

My question now if this is possible? Can I use the wires of an ethernet cable to sent multiple ouput signals to my relays?

If not is there another way so that I don't need a I/O module?

OR how can I communicate with the Hardware.

Any advice would be really appreciated!

Thanks in advance,
Best regards,
Michael

 

[BradtheRad]

Have you previously worked with temperature sensors? Relays? Heating elements?

Short description:
* Take reading from a sensor. Amplify if needed.
* Compare with desired reading.
* If temp is below your desired low threshold, send signal to relay to turn on heater.
If temp is above your desired high limit, then turn off heater.

It's a good idea to draw various wiring layouts, so you can find the most efficient wiring scheme.

Use ethernet cables if you have lots of them, and jacks too. You'll have to make written notes, for matching insulation color to each relay (or sensor). If I were doing it, I think I'd use telephone cable (2 or 4 conductor). It's cheap, easy to obtain, and easy to work with.

 

[MikeSv]

Hi and thank you for your reply.

Yes, Ive worked with sensors and relay before.
I usually use NI hardware, but for this project I want to avoid it.

If I use a telephone cable I guess I need something between my PC and The hardware?

Is that something you would do with some Microcontroller?

Best regards,

Michael

 

[BradtheRad]

A microcontroller is probably recommended as the central brain for your system. (I have no experience with pics or microcontrollers.)

It quickly gets complicated because:

* You must figure out how to provide power to your various remote devices.

* How many ADC inputs do you have? Do you need to build some kind of input switching among your sensors?

* How much power does your heating element draw? It is more efficient to have short wire runs. Each heater should be close to its own relay and power supply.

* How many output pins do you have? Do you need to build a board that will distribute On-Off signals to the relays?

* Can your SS relays be turned on by a PC/ microcontroller? You must experiment to make sure about this. If the relay needs more power then you need to install a transistor/ mosfet to do middleman duty.