Have you tried using DateTime.Subtract? This returns a TimeSpan object that has both values that can then be used. Cheers

For the price Annabooks is selling it for, You could buy a Kindle reader and all the books for the Netduino and still have money left over.

Nice idea!

Hello Bryan.
Here the answers:

• no, I'm not familiar with *that* project, although we're developing our own, which is similar;
• yes, you should able to interface easily with a Netduino just leveraging my Modbus library.

Hope it helps.
Cheers

Mario,

I have a couple of questions for you about your Modbus library. Being new to the whole world of Modbus, let me give you a little background as to what I want to do with it and maybe you can steer me in the right direction.

I'd like to use it to control my Electric Brew Kettle's heating element by setting the target temperature I want to reach and then read back the current temperature and whether the element is on or off.

As for setting the target temperature and reading the current temperature and if the element is on or off, I'm thinking I could use the ReadRegisters and SetRegister methods.

I've also been working on porting over the Arduino PID Library to provide a better control algorithm and would love to be able to set the PID settings, however they are all doubles and I didn't see anything in the Modbus spec that talked about sending doubles to a device, everything looks like integer values.

Any ideas on the best way to go about setting this up?

Thanks

After checking out the sourceforge project and Mario's ModBus library, I'm thinking of replacing the web based app on my brew controller with this. Should be great for an example on how to use both together.

I have a Temperature Monitoring Project out on codeplex that I put together for my Walk-In Beer Cooler. It might be a good start for what you want. You can find the code at http://diybrewerytem...r.codeplex.com/ Hope this helps you out.

If I remember correctly, The Netduino will see anything higher than 1V as True and this might be where your trouble is. Can you configure your voltage divider such that when the sensor is not triggered your below 1V? Guys, can you help me out with what the true voltage threshold is for On vs. Off on the digital ports?

Kristoffer, By default the Digital IO pins only return a True for High (3.3V) or False for Low (0V). If you want to read varying degrees of voltage you'll need to use one of the Analog IO Pins. These will return a voltage between 0 and 3.3V that you could then use to determine the proximity from the device. There are a lot of examples in the forums as well in several of the books on Netduino to help get you started. Good Luck and keep us posted on your progress.

One of the forums members did a pretty exhaustive test around ADC noise and that is probably what you are seeing. You can find his write up at http://highfieldtale...se-of-netduino/ Hope this helps.

I've been working on a new brewing project and have gotten far enough along to start showing it off to folks. I've been working on modifying an Electric Turkey Fryer that I can use to brew small batch of beer for competitions and such. I based the temperature control off of my previous DIY Brewery Temperature Monitor project and enhanced it to allow the user to enter in a temperature that the Netduino will work to maintain during the mashing process. I've also added buttons to control the system for those times when I don't have a network handy along with a LCD Display to show the current status of the system. I'm still waiting for the circuit boards to come back from BatchPCB.com so I can assemble the system in a nice control panel. You can read about it over at my DIY Brewery Blog at http://diybrewery.com

Thanks Guys, I thought I had read that somewhere, but I wanted to make sure before I went down that path. Right now I'm trying to keep from making any changes to the fryer unit if possible. The only thing I've done so far was to re-route the wiring to my Netduino Controller, everything else I left in alone. Down the road if I need to have more precise control over the heating element, I'll look into replacing the existing mechanical relay with a Solid State Relay that I can use the PWM feature on.

I'm in the process of building a brewing controller that will be used to control an existing heating element used on an electric turkey fryer. My goal has been to mod the existing unit without replacing much of the existing parts. As the system is now, the heating element is turned on and off by a 12VDC relay. I've got this working quite well by using a normal IO pin and turning it on and off. What I would like to do is as the temperature of the beer gets close to my goal temperature use one of the PWM ports to change the duty cycle from 100% to 50% on down to 0% as I get closer and closer. This way I'm hoping to reduce the amount of temperature drift in the overall system. When I started playing with the PWM port and varying the duty cycle I noticed that the voltage readings were strange, at 50% Duty cycle I was only seeing 1.6 volts instead of 3.3 volts. Maybe this is because I am using a multi-meter instead of looking at it with an actual scope. Does anyone know what I should be seeing? Also, is varying PWM duty cycles with a relay a really good idea? I've read where it's not an issue with solid state relays but I'm uncertain about normal relays. Thanks

It does not look to be available in print, I checked both Amazon and www.annabooks.com. However Amazon does provide a free Kindle E-book Reader for both PC and Mac if that helps at all.

I didn't see anyone else post about this, so I thought I would give everybody a heads up. A new book was released about the .Net Micro Framework called, Professional's Guide To .NET Micro Framework Application Development. I picked up a copy on Amazon on the Kindle for a decent price. It does include examples for the Netduino as well as other .NET Micro Framework devices. I wouldn't call it a beginner's guide, but its not that advanced either. It is based on a training program provided by Annabooks, they provide quite a few example programs to explain each section. So far, what I've read is pretty good for an intermediate guide. Here are the book details from the Annabooks web site: Professional's Guide to .NET Micro Framework Application Development By John R. Malin and Sean D. Liming The Microsoft .NET Micro Framework brings Microsoft’s embedded expertise to resource-constrained devices, allowing device makers to bring products to market faster and at lower cost. TCP/IP and Web Services for devices functionality makes the .NET Micro Framework a compelling platform for a new generation of smart, connected, service-oriented devices. Its compact footprint (as little as 64 kilobytes) and support for 32-bit embedded processors without an MMU help keep per-device costs low, and a managed driver model makes it easier to develop device drivers. .NET Micro Framework applications are written in C# using either Visual Studio 2010 or Visual® C# Express 2010 Edition. Professional’s Guide to .NET Micro Framework Application Development provides the most advanced treatment of the .NET Micro Framework SDK available. Over 40 hands-on exercises guide the developer through the tools and APIs available in the .NET Micro Framework SDK. Nineteen chapters cover the basic operation, hardware I/O support, basic networking, graphical interfaces, storage, and the final sample projects to tie the different features together. Example Visual Studio® projects are available for the most popular .NET MF platforms on the market. Table of Contents SECTION 1 – INTRODUCTION AND C# BASICS 1 WELCOME 2 DEVELOPMENT SYSTEM SETUP AND TARGET HARDWARE CHOICES 3 .NET MICRO FRAMEWORK OVERVIEW SECTION 2 – .NET MICRO FRAMEWORK SDK AND THE PROCESS LOOP 4 THE .NET MICRO FRAMEWORK SDK AND THE FIRST .NET MICRO FRAMEWORK APPLICATION 5 INNER PROCESS MECHANICS SECTION 3 – HARDWARE I/O 6 GENERAL PURPOSE INPUT/OUTPUT PINS 7 SERIAL PORTS 8 SERIAL PERIPHERAL INTERFACE (SPI) 9 PULSE WIDTH MODULATION (PWM) 10 ANALOG-TO-DIGITAL CONVERTER (ADC) 11 ETHERNET SECTION 4 – GRAPHIC USER INTERFACE 12 BITMAP CLASS 13 WINDOWS PRESENTATION FOUNDATION CLASS 14 TOUCHSCREEN AND INK SECTION 5 – STORAGE 15 FLASH STORAGE 16 EXTENDED WEAK REFERENCES SECTION 6 – PROJECTS 17 MIGRATE APPLICATIONS TO A NEW PLATFORM 18 ROBOT PROJECT: TRAXSTER II 19 ROBOT PROJECT 2: STINGER Hope everyone finds this useful.

I've been working on an Electric Brew System Controller that I used to replace the controller in a Cajun Injector Electric Turkey Fryer. I've been using a TMP36 sensor along with the built in thermistor that is built into the heating element. I water proofed the TMP36 sensor by using a 1 foot length of 1/4 OD copper tubing and a 1/4 copper cap. I used Marine Epoxy on both ends to help keep the water out. I really did not notice that big of a lag in the thermistor compared to the TMP36 sensor. They both seemed to be pretty accurate side by side once I figured out the proper coefficients for the Stein-Hart Calculations. I also found a simpler version of the Stein-Hart Calculation over at http://thermistor.sourceforge.net/ that might cut down on the CPU a bit. There is also a nice little program that will calculate the coefficients based on a series of resistance and temperature measurements in case you can't find a part number or coefficients for a thermistor you might be using. I know it helped me out quite a bit since the manufacturer does provide enough detail about the parts used to put together their unit. If you are interested in the source for the controller you can find the source at https://github.com/l...TempController. Currently it is for a Netduino Plus, but I'll more than likely be converting it over to a Gadgeteer device soon, since things are getting pretty cramped.

As far as source code, I'm going to try and load it up on to codeplex this week. Issue with loading up here is that the file size is too big and I'd have to upload multiple posts and If I update it, you wouldn't have the latest.

But I'll definitely update this post once I get it up on codeplex. In the meantime, if you need it you can send me a message via the forums with your email and I'll send it to you.

I took a little time this afternoon and put the entire project up on codeplex you can find source code, schematic and eventually documentation at http://diybrewerytem...r.codeplex.com/

Enjoy!

Hi Coding Smackdown,

It's possible to download the source of this project?

Thanks,

Ludo

As far as source code, I'm going to try and load it up on to codeplex this week. Issue with loading up here is that the file size is too big and I'd have to upload multiple posts and If I update it, you wouldn't have the latest.

But I'll definitely update this post once I get it up on codeplex. In the meantime, if you need it you can send me a message via the forums with your email and I'll send it to you.

I spent some time this weekend putting together a shield for the temp monitor circuit. I used a piece of tri-board, cut it down to the size of shield and then added the components. Attached are a couple of pictures of it. Hope you enjoy!

Here are a couple of links that discuss this process in some detail that might help you to make your routine more efficient. The last link actually has an entire library to provide the missing functionality for all of the decimal types. http://www.eggheadca...bledecimal.aspx and http://bloggingabout...-framework.aspx Hope it helps

I studied the NETduino HW a bit and found that DM9161A chip performs autonegotiation for Ethernet link establishment autonomously.

I'm wondering if maybe you've come across something that has always plagued systems. I know in the windows world auto negotiation has always been problem some for devices and I have worked with network technicians who have recommended that it be turned off.

Maybe we should look at adding the capability to set the port speed on the Netduino Plus. If the network folks are having people turn it off, maybe we need to provide similar capabilities to allow the device to coexist with all of the other devices on the network.

Actually if you do some searching on the web you might be able to find an old version of code that allows you to play back phonemes together to make speech. I did it way back in the 80s on a timex sinclair 1000 and it was better than the mechanical sounding chip processors.

This is a really good piece of work. Once you have it all documented it definitely should get posted to the WIKI. Thanks for sharing your idea!

If you are wanting to do it from within your program check out this post It talks about the NetworkInterface Class that allows you to manipulative the network settings on the Netduino Plus. http://forums.netdui...uration-options I'm getting ready to update my Temperature Logger to provide full network address configuration from within my web-base GUI. Once I finish the updates I'll post back here so you have an example.

Nevyn, Don't feel bad I resorted to buying a magnifying lamp this summer so I could read the letters on my components plus I have to use my multimeter to read my resistors.

My temp readings are all over the place. Can someone please double check my setup?

I experienced the same thing. You are probably experiencing some noise from the Ethernet interface.

There is another thread in the forum that discusses the issue in some depth.

http://forums.netdui...ading-accuracy/

It is best to hook a .1uF capacitor between 3.3V and Ground to help drop some of the noise. If that doesn't work add a 1mH inductor between the ARef port and 3.3V.

I still had a lot of noise from the senors so I ended up performing 100 reads of the port and then averaging the reading:

int totalReads = 0;

for(int x = 1; x < 100; x++)
{
totalReads += Port.Read();
Thread.Sleep(10);
}

float reading = totalReads / 100;

This seems to work pretty good and is pretty fast for normal monitoring. It may not be the best performance wise, but you can vary the number of reads until you get a good smooth value back.

BTW: Are the two outer leads of your sensor actually hooked to anything? Your circuit looks strange since the two side rails on my breadboard do not have any connection to the inner holes. Try moving the pins over to the first set of holes that your leads are connected to and see if that makes a difference. Take a look at the breadboard diagram I did of my circuit here http://forums.netdui...erature-logger/ the TMP36 is pretty much pin compatible with the LM35.

Cheers!