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1  Using Arduino / Project Guidance / Re: Some networking fun: 28 arduinos linked in a network on: November 21, 2012, 06:27:44 pm
Exactly what URL are you entering in the browser's address field?

I am entering 192.168.1.187 and the browser adds the http:// part automatically if the address I enter doesn't show up.  I have also entered some other things into the IP address field within the code including the endings 1.177 and 1.30

Ok I don't understand "...and then just use two wires from the arduino to the switch", can you explain? What type of wires and what kind of communication are they carrying (Ethernet, extension with cable between the arduino and the ethernet shield, ?)?.

You should be aware that standard for ethernet cables says 100 meter max length. It is not a hard cutoff but considering it is in a factory maybe interference will actually be a problem.

The gigabit switch is overkill but if you already have it and no use for it...
10 Mbps is enough for this task, that's why I urge you to look into 2nd hand market. Actually seems hard to find pure 10Mbps but 10/100Mbps seems cheap also. The problem is the shipping so if you can find any local supplier that is good. Looked at an ebay auction, 3 NETGEAR FS524. That is 3x 24 ports. Start price is 30 bucks and no bids yet. As an example.

I haven't tried out my ethernet shield yet but remember that it is far from a full blown web server. E.g. it says at the product page that it can handle "up to" 4 sockets simultaneously. If all the sensor arduinos reports their results via TCP it will quickly fill the central arduino. A PC in the center is a requirement.

By two wires I mean having literally two wires going to a switch.  These will most likely be some stranded shielded wire connecting the arduino to a relay, photo eye, switch, etc.  I understand I will have to deal with relay jitter but that can be done by putting a half second delay in after it reads the contacts open/close.


I was thinking about the factory... I didn't understand you were experimenting a thome. Sorry  smiley-roll-sweat

Yep, I plan on doing all my first tests at home and then bringing it out to the company.

I've been thinking of the network control here, and the cost of the devices. Ethernet simplifies some things, but is expensive, and still leaves you with a bit of programming to do.

Can the nodes be polled, or do they react to an event to transmit data?

If they can be polled, I believe I'd :
* Buy $4 RS-485 boards off eBay
* Give each node a node-id.
* Put each node in listen-mode (in RS485 terms)
* Use EasyTransfer for the transfers back & forth, as this simplifies programming, adds checksums etc. It also simplifies management of data types, you can send an arbitrary struct.
* Have the Master send a package to each node in turn, then have Master go to "listen mode".
* A node having received "his" package prepares his return data, enables transmit mode, sends data, and goes to "listen" again.
* The master receives data, handles this in an appropriate way, enables transmit, and repeats.
* The master needs to handle a time-out
* You might get electrical problems on the RS485 bus if a node gets stuck in transmit enable mode.

btw: the avrdude issue usually means that you have something hogging the serial port on the Arduino - a device is hooked up to TX/RX and conflicts with the IDE trying to use the same pins.

I was orrigionally thinking of making them all react to the switch closing but now that you mention it, it might be a better idea to have the arduinos count for 5 min then send and stagger the times they send out so the main computer isn't overloaded.
I already have some of the stuff for the ethernet setup.  I was searching around the office there and I found some spools of ethernet cable.  The previous computer technician always had a good stock of everything including a large box of canned air.  I guess his willingness to be ready turned out to be good for this project.  

What you describe is standard procedure for an RS-485 bus protocol.
What's your time frame to get this all working?

______
Rob



I have no time frame to get this done.  For all that matters I could put this off for several years and get by with it. 

Another idea I have been thinking of and have mentioned above is using a Mux shield.  I can run cables a long distance from the machine and put a slightly higher voltage into the lines like 7v so the wires' resistance brings it down to 5.  From the Mux shield I can use the arduino to output a serial signal to the PC and have the computer do the work or I could go  from the arduino to an ethernet shield to the LAN and have the arduino serve a webpage.
2  Using Arduino / Project Guidance / Re: Some networking fun: 28 arduinos linked in a network on: November 20, 2012, 06:30:42 pm
What do you mean by "computers don't recognize it as a web page"? Please explain what you're doing, in as much detail as possible. Are you trying to access the Arduino with a browser? Which browser? What URL are you entering? What happens on the screen - does the browser connect? Does it get an HTTP response back? Does the HTTP response include a page? Does the page render? If not, what is in the page source?
I mean that the computer (a mac running google chrome)doesn't recognize it as being a valid address.  I load the original example with the arduino software and change the IP address that it uses to 192.168.1.187.  The shield flashes like it is connected to the network but when I enter the IP address in the browser it doesn't even act like it found a server on its IP.
Do you have a proxy ? Is the browser configured to use it ? If yes, try to select "direct connection to internet". Ask the company sysadmin if you need help with these details.
There is no proxy around my house and our browsers work just fine although verrrrrrrrrrry slow due to the fact we live in the middle of nowhere.  I am currently using an Apple Time Machine for the network switch, so no issues with LAN speed.  I can't contact the sysadmin without looking like a seriously mentally ill child.  Reason why? I am the sysadmin around the house.  I would have to talk to myself.   I already have enough issues related to aspergers and autism, the last thing I need is to be seen talking to myself.
3  Using Arduino / Project Guidance / Re: Some networking fun: 28 arduinos linked in a network on: November 19, 2012, 10:42:41 pm
I have just bought an e-book about the arduino.  Up to this point I have been learning by reverse-engineering the code and haven't learnt much.  Now that I have some literature to go by I might actually be able to learn this.
4  Using Arduino / Project Guidance / Re: Some networking fun: 28 arduinos linked in a network on: November 18, 2012, 06:21:03 pm
Thanks everyone.  I have decided on ethernet.  We already have a 24 port gigabit switch that we can mount in the ceiling of the center of the building.  From there we can go the furthest distance the ethernet cables will go and then just use two wires from the arduino to the switch.  Simple, right? I have been playing with some of the stuff at home with our apple time machine to connect the arduino to the LAN, but for some reason the computers don't recognize it as a web page even though I'm running the examples included in the arduino programming software.  Is this due to the network collisions?  Its using just 8' of cable right now.  And one more issue, my 2nd arduino doesn't want to accept software.  I select upload and the computer compiles the program and starts uploading but stops and this shows up:
avrdude: stk500_getsync(): not in sync: resp=0x00
Does anybody know how to fix this issue? I have re-installed the driver repeatedly but still cant get it to work.
5  Using Arduino / Project Guidance / Re: Some networking fun: 28 arduinos linked in a network on: November 17, 2012, 02:19:33 pm
Say what? What have you actually done to measure the RF noise in the factory? Most industrial motors are probably three phase squirrel cage induction types that may not produce much RF issues. What does the HP rating of a motor have to do with its potential RF production?
We have taken radios that are tuned to a good strong radio station and brought them inside the building and the signal degrades to the point you can barely hear the music over the static.  My point is that radio won't work in there.  There are too many metal structures in there that would block the radio signal.  We would get into issues of the signal getting blocked by the 2-ton presses and all the other things in between.

Update: arduinos bought from Fry's Electronics and my dad is getting the ethernet shields from Radioshack.
6  Using Arduino / Project Guidance / Re: Some networking fun: 28 arduinos linked in a network on: November 17, 2012, 12:53:26 pm
Thanks for the responses.
Some fairly inexpensive radio transceivers  (  RFM22B or the SIM20 433 MHz,  or the 2.4 GHz RFD21733 )  can be connected as a mesh with multiroutes, aknowledge, and autoresend.

I get 500m from the SIM20 outdoors, but it might be better using the 2.4 GHz   does WiFi work OK in the factory ?  its basically the same frequency.
A standard RF circuit will not work in the environment I plan to implement.  Have you seen the inside of your standard cereal factory?  Think of all the motors that drive the lines and multiply their HP by around 30-600 and you get what I'm working in.  The factory manufactures puzzles so we have a large amount of motors and controls running an this will be the first arduino ever present in the factory.  Almost all the systems there are industrial-grade PLC's from Allem Bradley or Mitsubishi.
What is the spreadsheet for? I mean, what calculations is it performing and what is being done with the results?

Although you've specified that the results must be displayed in a spreadsheet, use of a spreadsheet is a solution not a requirement; the fact you're also asking for 'live' updates make me suspect the spreadsheet is not actually suitable for you. What is the actual requirement here?

Do you  want a tabular display of the counters in some order? Over some period? Any of that user-defined? Charts of the rate of change or absolute values over time? The real requirements will imply the most appropriate way to store and present the data, and it may not be a spreadsheet.
My dad wants it in spreadsheet because that's what his employees know how to manipulate.  He wants it to be user friendly.  I told him repeatedly that Spreadsheet isn't designed for this stuff, especially with it being live.  I'm thinking I will have to make a web interface that the arduinos link into with actual live data rather than programming a batch file to reopen a spreadsheet file every 5 minutes.  Just another thought, if I got a Mux shield linked to an arduino and connected that to the PC, would that be about ideal for something like this or would it be more of a hassle to do that?  I'm thinking of how hard it will be to integrate all the connections from the different arduinos to one page.

Seriously though, has anyone modulated laser pointers?  and what range is possible?   Of course there would be environmental interference from rain and mist, but I have a specific project I want to test sometime.
Lazer pointers have been modulated before with an extremely simple circuit containing an op-amp and an audio transformer connected to the lazer.  I tried it with some success.  It would have been better if I had an op-amp though.  The range was fairly limited since I couldn't keep it aimed correctly for more than 10 minutes.  I have heard of some people using small telescopes with a photoresistor/photodiode connected to the eyepiece.  They would take a light bulb like you would find in a scrolling billboard with the light grids and turn it on and off with amps designed for speakers.  They were successful at transmitting audio with a half-decent quality of sound.

And a side note, my dad is going by Radioshack to get an arduino for me to start learning.  I already have a breadboard so no issues there.
7  Using Arduino / Project Guidance / Re: Some networking fun: 28 arduinos linked in a network on: November 17, 2012, 12:21:44 am
I figured that since the Xbee runs in the ghz range it would be less susceptible to RF interference by motors.  Can I get a small list of pros and cons of each of the three connection types you posted?  Oh and btw my dad also wants the data to be live on the spreadsheet.  I am not sure if that is possible.  Does anybody know?
8  Using Arduino / Project Guidance / Some networking fun: 28 arduinos linked in a network on: November 16, 2012, 11:56:35 pm
Hi, I am new to the arduino platform.  I have been using a Lego Mindstorms NXT with the software that comes with it and have some experience in batch programming.  My dad co-ownes a manufacturing company and wants me to design a system for him that can take the data from a switch (SPST and closes when cycles) that counts how many times the machine cycles and put it into a Microsoft Excel spreadsheet with each machine having its own count display.  We have a price limit of about $5000-$8000 and want a system that can be expanded upon to around 30 machines easily.  The arduino was my natural choice since I have heard of it being used in many projects.

The first thing I want to do is decide what interface to use.  I do NOT want to have a few arduino megas that are monitoring multiple machines.  It would take out the part of adding to the size easily.  I have thought of using XBee modules on some fios, ethernet connection to a large hub dedicated to the arduinos, and coaxial connections.  Connecting the Rx and Tx pins together is not an option as the area this will have to cover is a rectangle of about 1000yd by 300yd.  Standard RF circuits are also out of the question as they would be interfered by the large 200hp motors and the large collection of other noisy goods. (both physically and RF)

My plans are to first decide a parts list, make a hello world demonstrating that this is possible, and finally buy the rest of the parts to make it possible.  You will know when I buy them as stocks of one arduino or another will drop dramatically.

Just remember when you respond, I do not know much about the programming language and am still learning it.  I plan to buy two arduinos tomorrow, a couple ethernet shields, and an xbee set.  And just out of curiosity, what is the record of the most arduinos connected into a network like the one I'm planing on?
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