Temerature sensor/thermostat 4-20mA

[dreamer]

I’m looking for a temperature sensor/thermostat with two analog (4-20mA or à-10Vdc) outputs: one for the setpoint and one for the room temperature. No other features needed.
A wireless model would be very nice but not necessary.
Can anyone help me?

 

[widelto]

If you are ar going to connect it to a plc, you just need one output. Tell us about your project.

 

[dreamer]

Thanks widelto,
This is a regular HCAV functions we need but it is a part of a monitoring system which is built around Wago controller running Codesys. We also need full control over proportional valves, pump speeds and temperatures. Therefore we can’t work with standard closed thermostat systems like Honeywell, …..

I think you are right saying one output is enough if this output give the difference between the setpoint temperature and the real environment temperature with “-“ and “+” information. In this case we have no information about the real room temperature.
Can you explain your idea with one analog output.

 

[widelto]

Setpoint must come from you ( hmi, pc , plc program etc ) not from another device. Use your plc, your process variable together with your setpoint to control your process.

 

[dreamer]

That’s not possible. Every room mus be able to set the temperature.

 

[Earthscape]

I use a Hydac temp transmitter for A similar process, 4-20 output. That said, are you sure that your air-handler will go in to active heating and active cooling for every room ? Sounds like you're probably using this for a BAC-Net application ? If so, look in to KMC 5800 line. A 5801 may be just what you're looking for.

http://www.kmccontrols.com/docs/Brochure_BAC-5801-02_SB-003C.pdf

 

[widelto]

Dreamer: I get what you want, I´ve seen devices like that, try honeywell.

 

[The Plc Kid]

Dreamer

Sounds like you have a central system you are controlling with a VAV or underfloor controller for individual heat and cool room by room am I correct?

You may want to look at fieldserver http://www.fieldserver.com/products/SlotServer/SlotServer_ControlLogix_Module.php

With this module you can get tstats that work on BACnet, LON Works,BAS or JCI and the wiring would be much more simple easier to troubleshot and be much more accurate than what you are thinking

 

[dreamer]

Widelto: I bought already a Honeywell “CMT957M1011” for testing but these have only a “OpenTherm” 2 wire output. As far Honeywell informed me they have no solution. Which model do you have in mind?

 

[shooter]

for the temp you can buy anything you like with a price, however as i make precision temp readers (yes with a wago 750 series) i use a simple cheap converter with a XTR105 inside. and a good Pt100.
For the setpoint you can use a mA calibrator with a potmeter in it.
btw you only need one expensive analog input for these slow processes. I use small relais to switch over between rooms.

for the wago look at www.oscat.de this way you do not have to write software
i am from holland so cheap is rule. but it is reliable.
and yes i do speak german.