Help required - Logo 8

Hi Guys,

It's being a few years since I've touched on PLC's and now I need to get up to speed again

What I'm looking to do is connect a  0-10v thermocouple/Humidistat to Logo 8 and if possible have a variable output to drive a fan array

Any help would be greatly received

Thank you 

Thank you for your quick reply !

What we are wanting to do is vary the fan speed depending on temperature levels

The fans will 240v so switched would be better................but I'm open to suggestions

Thank you

I'm sorry, but I do not understand what you want to do.

Do you want to 240V fan only on / off (over a temperature limit) or do you want the fan control (for example, via a 0-10V control input to the fan, if present).

Again the request: Describe clearly what you want to do.

Sorry.........

What we need is to have the fans to  run at a variable speed (100%, 50% and 25%) depending on the temperature and humidity input

The fans we are using at the moment are 240v AC and are switched from a thermostat and now need to make the system more efficient

I have attached a PDF of the new sensor we are thinking of using

Thank you

If it is ordinary 240VAC fan, then you can not regulate it with the logo.
Then you need speed controller for fans.
The logo can only:
- On / off via digital outputs.
- A regulated control signal output via an expansion module with analog outputs, either 0-10VDC or 0 / 4-20mA.

But they can not regulate 240VAC.

Thank you for clarifying that

If we used 24V fans could we do it then ?

Also can we input the thermocouple/Humidistat  directly to the Logo via the digital inputs ?

Thank you again

Nalabala

Thank you for clarifying that

If we used 24V fans could we do it then ?

Also can we input the thermocouple/Humidistat  directly to the Logo via the digital inputs ?

Thank you again

Against:

If it is ordinary x VAC or VDC fan, then you can not regulate it with the logo.
Then you need speed controller for fans.
The logo can only:
- On / off via digital outputs.
- A regulated control signal output via an expansion module with analog outputs, either 0-10VDC or 0 / 4-20mA.

But they can not regulate x VAC orVDC .

thank you again for your input......and patience !

I think we need to rethink the fan control so could we concentrate on the thermocouple side

I have attached the PDF of the sensor we are wishing to use and any help with the connection/circuit would be great

Thank you

Here are 2 possible solutions.

Solution 1:
Switching on and off of fans over limits.

Solution 2:
Controlling the fan speed for a PI controller when the fan is adjustable.

Solution 1 in attachment, Solution 2 attached at next post.