Author Topic: Z-wave device with 4-20mA analog output?  (Read 995 times)

Offline mervander

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Z-wave device with 4-20mA analog output?
« on: February 22, 2017, 06:58:54 am »
Hi All,

This is my first post.

I'm about to launch into home automation with a view to improving self consumption of solar PV generation. I'd like to use some "industrial" devices that require a 4-20mA analog control signal.

Is anyone aware of a Z-wave device that has this output?

I can go some way with the 0-10V output from a Qubino Flush Dimmer as some the inputs of some devices can be configured to either voltage or current. This is however not true for all and having 4-20mA gives access to a much wider range of devices.

The signal converters I've found that can convert 0-10V to 4-20mA were all designed for industrial use and therefore too expensive. Besides, adding another device in the chain would not be very elegant.

I intend using a Vera Edge controller. If there is a cost effective way to get a 4-20mA output from it through some means other than a Z-wave device I would also be interested in that.

Thanks for your time.

 

Offline RichardTSchaefer

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Re: Z-wave device with 4-20mA analog output?
« Reply #1 on: February 22, 2017, 02:33:13 pm »
You would need to design something that is driven from a dimmer.
You might be able to find a wifi driven 20ma solution then interface to Vera.

Offline Chrisfraser05

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Re: Z-wave device with 4-20mA analog output?
« Reply #2 on: February 22, 2017, 04:48:26 pm »
I looked down this road myself a while back and came back with very little.

Offline mervander

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Re: Z-wave device with 4-20mA analog output?
« Reply #3 on: February 22, 2017, 11:52:59 pm »
Thanks Richard and Chris,

To me this is a very real gap, but maybe it seems worse to me being from the petroleum refining industry where almost anything can talk 4-20mA analog.

Offline Chrisfraser05

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Re: Z-wave device with 4-20mA analog output?
« Reply #4 on: February 23, 2017, 03:58:10 am »
I hear ya. I'm an electrical/electronic commissioning supervisor on oil drilling rigs.


To be honest we are used to using 4-20ma stuff as it's a safe standards for low energy spark proofing.

It's expensive and simply not needed in non explosive environments.
0-10v tends to be the standard otherwise.

There are Fibaro modules that deal with Zwave to 0-10v in and out.
There are a range of components designed to work with a Pi or Arduino that work with 0-10v.

Offline JohnRob

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Re: Z-wave device with 4-20mA analog output?
« Reply #5 on: February 23, 2017, 07:22:11 pm »
As you have found, the 4 - 20 ma interface is for long and noisy analog control in an industrial environment.  Not much use in home automation.

If you want to work with 4 - 20 ma signals; my suggestion to create a 4 - 20 ma output from Vera would be to use the Fibaro RGBW.  This unit will output 4 independent PWM signals (@244 Hz).   I think this is fast enough to be able to be R-C filtered to create an adequate 0 to <tbd> analog signal.  From there you should be able to find a 4 - 20 ma converter.

This unit has 4 analog inputs as well.   A simple resistor from an external 4 - 20 ma source can be sensed and read by Vera.


Good luck

JohnRob


Offline mervander

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Re: Z-wave device with 4-20mA analog output?
« Reply #6 on: February 23, 2017, 11:58:00 pm »
Thanks John,

I'll ask my instrumentation buddy at work to "translate" your post for me - I'm a chemical engineer with somewhat limited understanding of these things ;)

My two intended applications are a VFD on my pool pump and a proportional solid state relay to vary the duty on my water heater element.

The VFD can be configured for either 0-10V or 4-20mA input. The SSRs are available in either 0-10V or 4-20mA input models, but I can source the 4-20mA model for about $60 less than the 0-10V model.

I've got two water heaters to control, so was hoping to save the $120 by finding a simple way from Z-wave to 4-20mA.



 

Offline JohnRob

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Re: Z-wave device with 4-20mA analog output?
« Reply #7 on: February 24, 2017, 12:24:03 pm »
Hi mervander,

You've got a fancy pool pump there!

Vera and home automation in general do not have much analog capability.  There are a few folks who chose to "roll their own" sensors etc but the majority of folks stay in the digital world.

Things you might consider:
  • Depending on where your pool pump is (mine was in my back yard some distance from the house).  Getting a reliable Z Wave signal to the pool might be an issue.   That leaves keeping the Z wave module in the house and running the control signal to the pump.   For this, the 4 - 20 ma signal excels.   But you will find the conversion from Z Wave (perhaps PWM) to 4 - 20 ma a challenge.
  • Before embarking on a direction with the pool pump, find how it handles transient commands.   If the Vera control drops out and comes back quickly etc will it damage the pool pump?
Another though you might consider,  Is it possible to limit the control authority of the Vera by pre-selecting 2 or 3 fixed settings.  You can come very close to 4 - 20 ma control with a 24Vdc power supply (small wall wart) a few resistors and the Quibino RGBW.
Your instrumentation colleague should be able to help else I can be more specific if you wish.


Good luck


JohnRob





Offline mervander

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Re: Z-wave device with 4-20mA analog output?
« Reply #8 on: February 25, 2017, 01:46:09 am »
Thanks John,

Fortunately the pool and pump is right next to the house, so Z-wave range shouldn't be an issue.

Good point you make about interruption of the Vera control. I haven't bought the VFD yet but have one in mind. Will check out the documentation.

Best,
Francois

Offline tiaanv

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Re: Z-wave device with 4-20mA analog output?
« Reply #9 on: March 13, 2017, 06:55:13 am »
Hey @mervander


So some homework for you to do....
http://docs-europe.electrocomponents.com/webdocs/1236/0900766b812364f6.pdf



This can easily be driven by 0-10V input Qubino 0-10V dimmer or alternatively as suggested Fibaro RGBW module.  Alternatively (hi-tech), it can be controlled by rs-485 (mod-bus), rs-485 wifi interface, with some fancy code running on the VERA and talking to a RS-485 interface, but this is overkill in your specific situation, as simple control of the motor RPM is more than adequate.


Regards
Tiaan
« Last Edit: March 13, 2017, 06:58:35 am by tiaanv »
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