Mitsubushi AL2-24MR-d PLC - Analogue temperature sensors

[cieranfraher]

Hi I am using a Mitsubishi al2-24mr-d plc to control a project at college. I am thinking of using LM35 or LM61 temperature sensors as inputs and the plc needs a voltage analogue input from 0v-10v. Does anyone have any advice for me? I know I will have to build a circuit to make this happen, however I don’t know what components to buy and how to configure the circuit.

Any help would be very much appreciated

 

[cl10greg]

You could use the LM35 pretty easily. Supply the IC with at least the voltage output you want the range of (10V in your case). Depending on your temperature range you want there are two different circuits; One for 2 to 150C and another for the negative range. The negative range has an issue because it gives a negative output voltage that you would either have to convert or handle in the controller. The LM35 has the circuit built in to convert the temperature to a linear output so it does most of the legwork for you but like I said it based on your system needs and the temperature range you are looking at.

 

[cieranfraher]

You could use the LM35 pretty easily. Supply the IC with at least the voltage output you want the range of (10V in your case). Depending on your temperature range you want there are two different circuits; One for 2 to 150C and another for the negative range. The negative range has an issue because it gives a negative output voltage that you would either have to convert or handle in the controller. The LM35 has the circuit built in to convert the temperature to a linear output so it does most of the legwork for you but like I said it based on your system needs and the temperature range you are looking at.

Hi thanks for your response.

My project focuses on extracting hot air via a fan from one room and transferring it into another room through some trunking, this heat will be generated from an independent heat source and controlled by a thermostat separate from any components controlled by the plc.

The sensors will detect the heat produced and act accordingly; I’m just in a bit of a mess trying to figure out how to set the sensors up to act how I want them to.

So the set point temperature can be any temperature as it is just a proof of concept. I am thinking of setting it up to turn the fan on at around 28 degrees centigrade.

I do not have a lot of knowledge in this area as I am a trainee, I have written the program on the plc and it works, I would like some advice on how to create the circuit for the LM35 and the voltage outputs that would represent 30 degrees centigrade.

Thanks again Cieran