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Old 12-19-2015, 12:11 PM   #21
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After following Twisted Tree's blog outfitting his new Nordy I believe I'd run not walk away from anything to do with N2K network interface.
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Old 12-19-2015, 01:26 PM   #22
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If you use RTD or NTC Sensors

You need to specify a sensor wire type. Some PLC use twisted pair some use shielded wire. Cannot be run along or near HV AC >24VAC. etc etc.

In the perfect (industrial) world 4-20 MA sensors are used. As long as you have 20 MA in your circuit you can have a two mile long sensing circuit.

Quote:
Originally Posted by R_p_ryan View Post
The thermocouple I posted includes the converter board, so it should play well with an Arduino.

Regarding the resistance/voltage on a k-type thermocouple you are both correct! I respect the analog world, but I grew up digital.

Nice link to the hose coupling with the thermocouple adapter. That would fit nicely on my raw water side, but the FW side is 2". I don't mind tapping the steel pipe or brazing on a threaded fitting.

I looked around and didn't see any similar projects. I'd host it on GitHub, and probably start by using design for the tach: Arduino RPM Counter / Tachometer

I dunno if any of you are programmers and would be interested in contributing? With GitHub we can have as many people as we want to help out. Arduino uses a C style language and the IDE is free to download.
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Old 12-19-2015, 03:31 PM   #23
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These are great ideas.
The ScanGuage display is similar to what I was thinking. A compact unit with a button to display the next sensor's output. Thanks for the link to it, the user-interface provides some guidance.

The PLC route is definitely something to consider. I've used a PLC before but found it more difficult to program than an Arduino. The device could be SignalK-compliant, and provide a JSON endpoint to return engine statistics. And putting it on wifi is also a great idea since it could send me a text message when my bilge switch turns on. I'm thinking an Agile approach makes sense, and we can focus on small iterations.

The vastness and cheapness of the Arduino platform is appealing, as is the open-source nature of it. With all the shields available there is an unlimited degree of flexibility. I think Waspmote is pretty interesting too.

Regarding reinventing the wheel, we should disclaim this project is for the maker / do-it-yourself type and the system is not to be depended on when safety is at stake. If you're looking for a proven, purpose-built, marine-grade, bolt-on device then this isn't it. This is for the person who enjoys creating things, is on a budget, and wants more information from his/her engine.

Stubones99:
Thanks for the information. I agree with the DC-DC converter. You bring up a good point with the opto-isolation. I've been assuming this is for a marine diesel, so there wouldn't be the EMF of a gasoline ignition. Can you explain the need for opto-isolation? I don't know how we would be able to provide opto-isolation of the arduino from the sensors. Each sensor will have a pull-down resistor that should help dissipate stray energy. Currently I have the Arduino connected to my EGT using a simple K-type thermocouple with a small converter board and haven't had any issues. I'm playing with the magnets and the sensor for the tach - I could imagine getting stray energy from the alternator. Can you please explain more about the opto-isolation?

The first iteration:
What do people think about oil temp, tachometer, and EGT as the first three sensors? I'm thinking the Arduino would be mounted in a case on the bulkhead in the engine room, with a compact display/button similar to what_barnacles suggested in the ScanGuage design. The display/button would be connected to the Arduino using a CAT-5 cable. The display could be something like a 16X2 in a small enclosure.

Thanks,
Robert
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Old 12-19-2015, 06:57 PM   #24
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This would be the layout of Version 1.0. The basic architecture is to off-load processing to break-out boards. The break out boards do the work and can be queried from Uno. This reduces coding and complexity. This frees up pins and simplifies the construction and cost. Materials cost less than $100, but that doesn't include wire, solder, enclosures, etc.
Features:
  • Compact, dash-mounted display
  • Digital RPMs
  • Oil Temperature
  • Exhaust gas temperature
  • Raw water in
  • Raw water out
  • Engine coolant leaving engine
  • Engine coolant leaving heat exchanger
  • Engine room temperature

It supports:
  • serial display board with 2 lines of 16 characters
  • Next button
  • Thermocouple break-out boards for EGT and Oil temp
  • 1-wire bus for several temperature sensors, max temp 250F
  • Basic USB car charger for power supply

Please let me know if the is correct feature set for V1. I would like V1 to be successful and reliable; not complex and abandoned.

Assuming we have agreement on the V1 feature set I'll search for display enclosures

I think version 2.0 would create some intelligence, such as a red light or buzzer when a value exceeds normal.

From looking at all the low-cost add-ons I'm wondering if the UNO is going to have enough pins to support the future. It would be easy enough to upgrade to a Mega if neccesary and have wasted too much time on trying to "future proof" this.
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Old 12-19-2015, 07:22 PM   #25
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The opto-isolation will prevent any accidental 'let the smoke out' events when power from another source gets into a sensor wire.

Wiring should be high temperature (insulation) since any accidental contact with exhaust manifolds, etc. could result in shorts which could smoke the D/A shield.

When you say raw water in and out, I assume temp and not water flow?

you also may want to consider a temp sensor on the shaft seal (packing temp).

Also, a temp sensor for engine room? fire sensor?

And you may want to make the provision available for twin engines (two arduino)

plan on being able to log data points to be able to create a "normal" for each sensor. That way, you can quickly see a rising / falling trend and sudden out of normal data ranges.

I will see if I can get the code for an old compiler / macro language I wrote many years ago. I think I could adapt it to be able to do ad-hoc coding.

What OS will the Arduino be running? What dev kit would you start with?

My son in law is an arduino & android developer (current) and I'm ancient developer from DOS, OS/2, Windows, and a bit of IOS development lately. i think this would be a fun project and would enjoy tinkering with it.

While I don't have a boat and can't get out on one now (medical) my brain wanders aboard almost daily

STu
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Old 12-19-2015, 07:24 PM   #26
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Quote:
Originally Posted by BigJim View Post
You need to specify a sensor wire type. Some PLC use twisted pair some use shielded wire. Cannot be run along or near HV AC >24VAC. etc etc.

In the perfect (industrial) world 4-20 MA sensors are used. As long as you have 20 MA in your circuit you can have a two mile long sensing circuit.
BigJim,
Thanks for the info. I know very little about RTDs. Currently I have a low-cost, stainless steel encased Type-K thermocouple for the exhaust. Do you think I should use an RTD instead? I am planning on having the Ardiuno on a bulkhead in the engine room so the wire lengths would not exceed 8 feet.

For sensors that are never exposed to 250F I was planning on using the electronic "one-wire" protocol with digital ds18b20 sensors

This raises a good discussion on temperature sensors:
Thermocouple vs RTD vs ds18b20

I am no expert on this and these are thoughts about the different temp sensors
  • I don't know enough about RTDs to comment
  • Thermocouples tolerate extreme heat and require a break out board
  • DS18B20 is very accurate and low cost. A single pin can be used to query many sensors

Please let me know if I've gotten any this wrong, and please let me know if the RTD should be included.

Thank,
Robert
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Old 12-19-2015, 07:47 PM   #27
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maretron has a switch closure sensor for water flow. it is a plastic housing and should work to report if water flow drops below a set point. I think it is a paddle / spring thing where waterflow has to get to a point to push the paddle down.

How many current loop circuits does the shield support?

Are there digital loops available? If so, how many?
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Old 12-19-2015, 07:49 PM   #28
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link comparing thermocouples to RTD sensors.
http://www.omega.com/TEMPERATURE/pdf..._SPECS_REF.pdf
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Old 12-19-2015, 10:01 PM   #29
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twisted pair shielded for the temp sensors should be fine. diesels really arent that noisy electrically. with the rtd's you are back to what I said originally, needing to design interface circuits.
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Old 12-19-2015, 10:20 PM   #30
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Old 12-19-2015, 10:40 PM   #31
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Quote:
Originally Posted by R_p_ryan View Post
Assuming we have agreement on the V1 feature set I'll search for display enclosures
I'm developing a marine enclosure for the iPad, here's crude pics of it; I contemplate it working best as an integrated flat controller. My concept is that this (Poort enclosure) form factor can replace a lot of the traditional dash and display devices, as the migration to tablets continues. A $50 enclosure and an old iPad are a possible platform you can leave in place. Getting the engine sensors incorporated will be a major hurdle. - Dwight



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Old 12-20-2015, 09:35 AM   #32
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iPads don't work well in direct sunlight. If you do this for a flybridge, make sure to make a sun shield too. Perhaps a polarized screen protector will help in bright light?

I know my iPads of different generations are poor reading in a car unless you're far from the window.

Stu
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Old 12-20-2015, 10:39 AM   #33
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Is an arduino device stack going to survive in a hot engine room with the other airborne contaminants like salt water vapor, oil, etc.?

While this may be a fun start at a m&c system, people will start depending on it... So we need to think operational durability up front.

Is there an environmental case for the Arduino stack? I am not comfortable with the end user having to connect tinned wires to each board and then stack the devices back together. I would say that there should be pigtails that lead to a connector strip on the outside of an environmental case, and all sensor connections would be connected outside the case. Or have some weather tight gland to seal the wiring as it comes into the connector strip.

You should also plan on sensing battery voltage on one or more banks.

Stu
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Old 12-20-2015, 11:44 AM   #34
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I am interested and have subscribed (I have an arduino onboard as an inexpensive weather system interface - works well).

Have you considered using the arduino for sensor/device interfacing only, with a consolidated data stream to a pc/laptop? A small companion program on the PC would allow a lot of flexibility in display and data logging / trending. Low power laptops are pretty inexpensive. (I have even picked up a number of free ones once they are no longer of use in the business world). For futures, the arduino data stream could be NMEA 0183 - pretty easy for the arduino to do.

An interesting project. Thanks for posting!
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Old 12-20-2015, 01:56 PM   #35
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Quote:
Originally Posted by stubones99 View Post
Is an arduino device stack going to survive in a hot engine room with the other airborne contaminants like salt water vapor, oil, etc.?

While this may be a fun start at a m&c system, people will start depending on it... So we need to think operational durability up front.

Is there an environmental case for the Arduino stack? I am not comfortable with the end user having to connect tinned wires to each board and then stack the devices back together. I would say that there should be pigtails that lead to a connector strip on the outside of an environmental case, and all sensor connections would be connected outside the case. Or have some weather tight gland to seal the wiring as it comes into the connector strip.

You should also plan on sensing battery voltage on one or more banks.

Stu
I totally agree on the right kind of case for the arduino stack. I was thinking there would be terminal block on the outside, like this: http://www.pcb-terminalblock.com/pho...m_300v_20a.jpg

As for the project box, it should be a sealed unit. The terminal block above would be fastened and gasketed to the outside. The screw-on connections would be on the outside of the box, and the terminals would be on the inside of the case. Those terminals could be soldered in to the stack.


Here is a diagram of the proposed V1:

In addition to battery voltage, what other simple senors would you like to see in V1?
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Old 12-20-2015, 02:18 PM   #36
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Lot's of great questions and points. My responses are in line

Quote:
Originally Posted by stubones99 View Post
The opto-isolation will prevent any accidental 'let the smoke out' events when power from another source gets into a sensor wire.

Wiring should be high temperature (insulation) since any accidental contact with exhaust manifolds, etc. could result in shorts which could smoke the D/A shield.

I'm thinking plenum-grade CAT-5

When you say raw water in and out, I assume temp and not water flow?
Yes, but I've seen some cheap flow sensors that report volume, but I doubt it's marine quality

you also may want to consider a temp sensor on the shaft seal (packing temp).
Great idea, Would you recommend this in V1? Would be easy with a 1-wire sensor since it woudn't take more pins

Also, a temp sensor for engine room? fire sensor?
Engine room temp is included in V1. Not a fire sensor though. I was thinking a subsequent version but we take something off of V1 to accommodate the fire sensor. A small concern I have is when this system starts to take the place of what should be a proven marine grade system, like a fire alarm or carbon monoxide tester.

And you may want to make the provision available for twin engines (two arduino)

plan on being able to log data points to be able to create a "normal" for each sensor. That way, you can quickly see a rising / falling trend and sudden out of normal data ranges.
I'm thinking alerting is in Version 2, but that's only because I want to have something simple and easy for the first version to increase adoption. Using the data for alerting or logging is very valuable, but is a bit more complicated since it involves a configuration capability and storing a map of data to determine the trend.
I'd like to have a data logger capability in some future version that stores all the measurements, with a timestamp onto a flash card



I will see if I can get the code for an old compiler / macro language I wrote many years ago. I think I could adapt it to be able to do ad-hoc coding.

What OS will the Arduino be running? What dev kit would you start with?
The beauty of Arduino is there is no OS to concerned with. You just plug the board into your PC/Mac/Linux using a USB. Then you deploy the code to the arduino using an open source tool that is downloaded from the Arduino site. This is the same tool you can use for your IDE, so it you want to see the code or even change it, it's simple. As for the dev kit, I was thinking just the Uno board ($25)


My son in law is an arduino & android developer (current) and I'm ancient developer from DOS, OS/2, Windows, and a bit of IOS development lately. i think this would be a fun project and would enjoy tinkering with it.
With your DOS through IOS skills you would easily pick up arduino. There are thousands of tutorials on everything from "hello word" through voice recognition.

While I don't have a boat and can't get out on one now (medical) my brain wanders aboard almost daily

STu
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Old 12-20-2015, 03:03 PM   #37
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Quote:
Originally Posted by nmuir View Post
I am interested and have subscribed (I have an arduino onboard as an inexpensive weather system interface - works well).

Have you considered using the arduino for sensor/device interfacing only, with a consolidated data stream to a pc/laptop? A small companion program on the PC would allow a lot of flexibility in display and data logging / trending. Low power laptops are pretty inexpensive. (I have even picked up a number of free ones once they are no longer of use in the business world). For futures, the arduino data stream could be NMEA 0183 - pretty easy for the arduino to do.

An interesting project. Thanks for posting!
Yes, this is how I'm currently using it but I want something without the bulk of the computer. I run the EGT off the arduino and send the data feed to my PC via the USB. I was thinking a future version would host a simple NMEA 0183 stream, or SignalK as @stubones99 recommended.
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Old 12-20-2015, 03:19 PM   #38
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Another off the shelf solution is the Sensaphone web based products.

They take 4-20 MA signals, contact closures or or standard 2.8K or 10K RTD units.

No serious programming and the interface is through any web browser.

4-20 miliamp is the standard in the process control industry. There are very few analog signals (like pressures, or voltages) that cannot be easily converted to 4-20 using off the shelf components.

I have a web600 in service right now and can attest that it is a very easy to use, easy to interface to product that would fell the engine monitoring needs the OP presented today, with zero non industry standard components.
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Old 12-20-2015, 05:54 PM   #39
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Attached is the bill of materials and Arduino Uno pin mapping. Cost for the components, including all sensors, display, power supply, enclosures, etc is about $170 plus shipping from a few vendors. I did not yet find a connector strip for the external connections. So probably around $250 by the time it's all done.

There is sample code for all the sensors, so programming should be straight-forward, however I've always experienced some degree of troubleshooting.

The Sensaphone Web600 looks like it would make temp monitoring very simple, but it starts at $350, can only measure up to 168F, and would require a web browser on-board.

How does this price compare with other PCS system?

Thanks,
Robert
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Old 12-20-2015, 06:59 PM   #40
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Greetings from Down Under.

I am keen to join the project. There is quite a mature Arduino following/group in Australia at the moment.

I would like to add some additional sensors to my Lehman diesel such as water temp and exhaust temp. As well as transmission oil temp.

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