nopls
Posts: 1
Joined: Tue Nov 06, 2018 7:44 am

Read Temperature from Omron K3MA

Thu Nov 08, 2018 7:51 am

Hi everyone.

I need to read the temperature from the sensor in the attached image. Then set a trigger when the temperature exceeds a specified limit.
I've already set up IFTTT webhook notification on node red, so It's just getting the data from the sensor and monitoring on node red (Or any other method if it works)
I'm a newbie.

Thank you. :D
Attachments
20181031_084213.jpg
20181031_084213.jpg (141.72 KiB) Viewed 144 times

RattusRattus
Posts: 13
Joined: Sat Sep 29, 2018 11:27 am

Re: Read Temperature from Omron K3MA

Fri Nov 09, 2018 12:47 pm

if you turn the unit round you will find a nice clear display.
When the K3MA is turned on and connected correctly use Mk-I human eyeball to look at the display....


Seriously though...
Your question boils down to this:
"I have <device> and I want to connect it to my RPi. "

The question that you need to ask yourself:
Does <device> have an output that provides the data that you want to read from your Pi?
if it does then yes you can (you may need to convert the data provided / support the electrical interface)
if there is no output from <device> providing information that you want then no you can't just 'attach a Pi' and magically be able to extract all the information you want

In the case of the K3MA series panel meters there is an output, but it only gives alarm indication - this DOES NOT give you temperature

If you want to get a temperature reading into the Pi then there are other sensors that you can use not this panel meter.
If you want to hack This panel meter then you could
1) Use a PiCam and some OCR software to 'view' the front display
2) take the panel meter apart and 'grab' the BCD information being sent to the display using suitably buffered GPIO on your Pi.

/Andy

User avatar
mahjongg
Forum Moderator
Forum Moderator
Posts: 11000
Joined: Sun Mar 11, 2012 12:19 am
Location: South Holland, The Netherlands

Re: Read Temperature from Omron K3MA

Sat Nov 10, 2018 9:30 pm

You might not like this, but IMHO Rattus is right, the device does not seem to posses any kind of digital interface, see https://assets.omron.eu/downloads/manua ... ual_en.pdf

Andyroo
Posts: 433
Joined: Sat Jun 16, 2018 12:49 am
Location: Side of the hill in Lincolnshire

Re: Read Temperature from Omron K3MA

Sat Nov 10, 2018 10:25 pm

Only hope you have is a bit off the wall:

1) as above - Stick a camera so it can see the display and OCR it.
2) Program the temp to trigger the relay at your warning temp and pick the relay change up.

Section 3-6 has an example of programming the unit but it also checks for a lower temperature so it will need modifying.

Note as this is a ‘C’ model, you only have one relay contact and that may be needed by the plant so you need to check with the plant engineers to see how you tap in and feed an opto-isolator and then to the Pi. Without a lot more plant details I doubt folk would want to advise you on the relay link just in case :shock:

Best bet - replace it with a more modern unit that can interface to others...
Need Pi spray - these things are breeding in my house...

LTolledo
Posts: 709
Joined: Sat Mar 17, 2018 7:29 am

Re: Read Temperature from Omron K3MA

Sun Nov 11, 2018 8:53 am

You can still use the OMRON temperature controller "as a temperature display/controller" only.

to be able to use it and a Raspberry Pi, you need to connect the thermocouple wire to the from the OMRON temp controller to a temperature A/D converter connected to your RPi. Then use your code to read the data from the A/D converter and set the trigger points. You need to calibrate the converter so that the readings from the converter is "almost" the same as the OMRON temp controller (+ or - 0.5 degrees or better) depending on your preference.

you cannot use just any wire. There are several types of thermocouple wire. Wrong wire = erroneous data.

And no, you cannot insist on using just any wire.
"Don't come to me with 'issues' for I don't know how to deal with those
Come to me with 'problems' and I'll help you find solutions"

Some people be like:
"Help me! Am drowning! But dont you dare touch me nor come near me!"

Andyroo
Posts: 433
Joined: Sat Jun 16, 2018 12:49 am
Location: Side of the hill in Lincolnshire

Re: Read Temperature from Omron K3MA

Sun Nov 11, 2018 2:35 pm

LTolledo wrote:
Sun Nov 11, 2018 8:53 am
You can still use the OMRON temperature controller "as a temperature display/controller" only.

to be able to use it and a Raspberry Pi, you need to connect the thermocouple wire to the from the OMRON temp controller to a temperature A/D converter connected to your RPi. Then use your code to read the data from the A/D converter and set the trigger points. You need to calibrate the converter so that the readings from the converter is "almost" the same as the OMRON temp controller (+ or - 0.5 degrees or better) depending on your preference.

you cannot use just any wire. There are several types of thermocouple wire. Wrong wire = erroneous data.

And no, you cannot insist on using just any wire.
Sorry but I've seen that NOT work so many times (at -ve temps) as the original readings go to pot I would never go that way but past experience clouds my judgement here :lol:
Need Pi spray - these things are breeding in my house...

Return to “Automation, sensing and robotics”