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 Posted: May 11, 2012 - 11:56 AM |
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Joined: Aug 29, 2010
Posts: 291
Location: Dharamshala, India
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Hi,
I have few nodes connected on an can network. I am looking forward to read Temperature & pressure from one node & send it to other node.
What will be right sensors to use ? shall i use 4-20 ma sensor type as noise do not have much effect on current, so reading will be correct ?
Please suggest.
Thanks
Katoch |
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Posted: May 11, 2012 - 12:38 PM |
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Joined: Sep 04, 2002
Posts: 21257
Location: Orlando Florida
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| Is a node an AVR? What range of temperatures? If 250 deg F or less, an LM35 will work. Otherwise a Type K thermocouple an a MAX6675 on the SPI. Sensata and other companies makes pressure sensors that output .5 to 4.5V which can be read by AVR directly. |
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Imagecraft compiler user
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Posted: May 11, 2012 - 01:02 PM |
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Joined: Dec 30, 2004
Posts: 8763
Location: Melbourne,Australia
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| I would say 4-20mA would be the more common type of pressure sensor and you can get pucks that convert rtd or thermocouple to 4-20mA. As to what are the 'right' sensors to usr, don't expect us to do your job for you. You haven't told us much about your 'boiler' or the application or where you're located. So, i'd suggest you get Googling like most of us would and find the answer yourself or contact your local distributors for this sort of equipment. Realise that there could be specific laws and regulations regarding equipment for a boiler that we have no hope of knowing. |
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Posted: May 11, 2012 - 01:27 PM |
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Joined: Oct 15, 2005
Posts: 530
Location: Russia, Far East Siberia, Irkutsk
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katochd46 wrote:
Hi
Hello!
I can say nothing about the pressure sensor.
But I can say something about the temperature sensor. If noise protection is so important for you, why don't you take any digital one? For example, DS18(B, S)20? Of course, it depends on the environment (temperature range). |
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Posted: May 11, 2012 - 08:21 PM |
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Joined: Feb 19, 2001
Posts: 25899
Location: Wisconsin USA
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Quote:
You haven't told us much about your 'boiler' or the application or where you're located.
Perhaps this one?
http://en.wikipedia.org/wiki/Pressurized_water_reactor
http://en.wikipedia.org/wiki/File:Reactorvessel.gif
Quote:
PWR reactor design
Coolant
Light water is used as the primary coolant in a PWR. It enters the bottom of the reactor core at about 275 °C (530 °F) and is heated as it flows upwards through the reactor core to a temperature of about 315 °C (600 °F). The water remains liquid despite the high temperature due to the high pressure in the primary coolant loop, usually around 155 bar (15.5 MPa 153 atm, 2,250 psig). In water, the critical point occurs at around 647 K (374 °C or 705 °F) and 22.064 MPa (3200 PSIA or 218 atm).
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Posted: May 12, 2012 - 05:55 AM |
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Joined: Sep 04, 2002
Posts: 21257
Location: Orlando Florida
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| Hey! Be Nice now! You don't really know if he is working on the instrumentation for the Imperial Iranian Peaceful Nuclear Power Project. After all, he hasn't seen fit to add his city and country to his profile. If it turns out that his city and country is Qom, Iran, then all bets are off as to what temperatures and pressures he might want to monitor. |
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Imagecraft compiler user
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Posted: May 12, 2012 - 07:35 AM |
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Joined: Aug 29, 2010
Posts: 291
Location: Dharamshala, India
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Only thing i can say at present is is an boiler used for Textile industry, i have not seen it. One of my friend told there is an small scale client who have similar kind of requirement. I need to give some presentation to him this month.
Temperature range upto max 200 degree celcius we can say.
Boiler type Example:---
Example-1
Example-2
Measuer water level :---
I searched on the net & find that pneumatic sensor along with diffrential pressure transmitter we can measure water level.
Example_video
Measure temperature :---
4-20 ma termocouple sensor can be used.
Measure pressure :---
Controling all three & i/o flow of water & stream :--
PID can be implemented, in single loop.
Transmission of details to remote location/ If more than one machinary have to work in cordination then :---
CAN network can be used to transfer industrial data reliably in high noisy enviroment.
Please suggest. |
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Posted: May 12, 2012 - 08:29 AM |
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Joined: Dec 30, 2004
Posts: 8763
Location: Melbourne,Australia
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| Pleaee suggest? The solution is all of the shelf, certified and more reliable than would be economic for you to make yourself. Allen Bradley have their devicenet which is can, but personally i'd just go with ethernet. Even the small PLCs these days have ethernet and webserver builtin as an option.don't waste your time designing equipment for industrial use. |
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Posted: May 12, 2012 - 09:51 AM |
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Joined: Aug 29, 2010
Posts: 291
Location: Dharamshala, India
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don't waste your time designing equipment for industrial use.
Means you are suggesting to Assemble an already existing PLC & some opensource protocol like devicenet(which is implemented over CAN) or Ethernet for communication purpose
Quote:
Even the small PLCs these days have ethernet and webserver builtin as an option
These PLC are capable of only ON/OFF operations depending upon i/p condition. What if we have to go for developing single loop control operation, can they support it
How much a single loop cascade PID control on a valve that controls a tanklevel, control system from Honeywell TDC3000/processmanager cost to us |
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Posted: May 12, 2012 - 01:20 PM |
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Joined: Dec 30, 2004
Posts: 8763
Location: Melbourne,Australia
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You know your requirements - you do the research. ABB have a range of small PLCs with PID and pwm output. I think schneider and Siemens will have similar offerings as will mostvother manufacturers.
I'm not too sure that DeviceNet is opensource. It may be published, but probably not open as compared with modbus. |
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Posted: May 12, 2012 - 03:01 PM |
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Joined: Sep 04, 2002
Posts: 21257
Location: Orlando Florida
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| Just make sure it has a SCADA connection so the spooks can throw a monkey wrench in it if it starts doing something sinister. Time to fill out your city and country in your profile. In the meantime, look at the schtuff from Measurement Computing. Stand alone Data acquisition boards with networking. Ready to go. |
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Posted: May 19, 2012 - 04:46 AM |
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Joined: Aug 29, 2010
Posts: 291
Location: Dharamshala, India
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