Temperature Sensor suggestion ?

[JNTurcotte]

Hi All,

I made a post regarding my personal project.
I think it's started to make more sense in the direction I want to take.

But I would like to find a way to reduce the cost of the temperature sensor.

Since most PLC will only accept analog input, or will require expensive thermocouples input cards. Is there a way to lower my budget on this ?

Is there other solution than thermocouples + signal conditioner ?

My temperature requirement is
Functional range : 50-120F
Full range : 0 - 150F
tolerance : +- 1F (but could accept more if price does make a big difference)
Reading : Surrounding air/surface element (flexwatt heat tape)

Otherwise, do you have any suggestion for not soo expensive signal conditioner ? (0-5V ideally)

Thank You very much once again !

 

[wolverine1981]

Hello

You could look at using a plc as in your other post and use a temperature controller from Delta Electronics. I used this with modbus control and accessed all parameters. I also used a HMI directly (noplc) to monitor and control the temperature controllers to.

They are fairly cheap, might be your solution check out the link below for the DTC-1000, for more zones you add on up to a total block of (8). They are also 24vdc.


http://www.wolfautomation.com/produ...ature-controller-no-displaybrdelta-dtc-series

 

[milldrone]

But I would like to find a way to reduce the cost of the temperature sensor.

Since most PLC will only accept analog input, or will require expensive thermocouples input cards. Is there a way to lower my budget on this

Have you looked at a CLICK PLC (real timeclock version) and the Solo temperature controllers from Automation Direct. The software is free. Unfortunately the PLC does not have built in PID loops, but the temperature controller can do this on their own. The temperature controllers can have their setpoints controlled by the PLC via RS485 modbus. The real timeclock would be need for your seasonal and time of day control. The controllers can power a solid state relay to power the load.

 

[BobB]

I think the Mitsubishi Alpha can have inputs configured for thermocouples etc.
Check it out.
Be careful of non isolated loop powered transmitters - they can cause problems with analogue cards.

 

[Tom Jenkins]

I'm not sure how much it will lower your total cost, but RTDs are, in my opinion, more robust and easier to apply than T/Cs.

 

[OkiePC]

I recently used some of these in a meat storage cooler and I really like the easy of installation, accuracy, cost, and they're pretty responsive.

http://www.automationdirect.com/adc...ors/Temperature_Transmitters/TTD-20-N40160F-H

http://www.automationdirect.com/adc..._(with_M12_Cable_Connection)/RTD0100-06-010-H

 

[TConnolly]

IFM Efector makes a line of temperature probes that operate in that temperature range that ouput 4-20mA signals. I use a large number of them for tank temperature. They are reasonably priced.