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vortexe9000
Joined: 07 Jun 2010
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| 1 o |
 Posted: Thu May 05, 2011 12:04 am |
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sdfg
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SherpaDoug
Joined: 07 Sep 2003
Posts: 1640
Location: Cape Cod Mass USA
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| Posted: Thu May 05, 2011 5:46 am |
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It looks like you have a pretty good example right in your post. What problem did you find in it?
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temtronic
Joined: 01 Jul 2010
Posts: 9243
Location: Greensville,Ontario
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| Posted: Thu May 05, 2011 5:54 am |
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| As for software, CCS supplies some RS-485 examples in the 'examples' folder.Probably a good place to start. Be aware that ISIS,like all simulators will NOT perform like the PICs in the Real World.They are full of bugs and quirks....stick with real code in real PICs in the real world. |
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vortexe9000
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| please Help me ... |
| Posted: Thu May 05, 2011 7:36 am |
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hjk
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vortexe9000
Joined: 07 Jun 2010
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| Thanks |
| Posted: Thu May 05, 2011 4:08 pm |
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please a simple code in CCS for numerical DATA and message
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ezflyr
Joined: 25 Oct 2010
Posts: 1019
Location: Tewksbury, MA
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| Posted: Thu May 05, 2011 6:35 pm |
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Hi,
I have a remote relay project that utilizes multiple 'nodes', and a single 'master' in a 1/2 duplex arrangement. I have defined my own 'protocol' as follows:
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// Here we have the Node command set.
// #N00:Q<CR> <----- Query Command - Response is !N00:Q0,0:00000<CR>
// #N00:R<CR> <----- Reset Command - No Response
// #N00:S0,0<CR> <----- Set Command - Response is !N00:S0,0<CR> - basically an echo
// #N00:V<CR> <----- Version Command - Response is !N00:VX,Y
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Each node has two relay outputs, and the 'Set' command is used to control them. The #N is just a pre-amble. The 00 is the desired node address (eg. 01, 02, or 03). Q, R, S, and V are the various command types I have defined. Everything else is data, such a 0,0 which turns both relays OFF with the Set command.
The 'node' module uses a serial interrupt to fill a receive buffer with incoming data. Each command always starts with a '#' character, and ends with a <CR> (carriage return), so it's easy to know when a complete command string has been received. Once the valid command string has been received, I first validate the address (the 2nd and 3rd characters of the command with each node having a unique address set by DIP switches) , and then act on the command type (determined by the 6th character). Here is a snippet from the Switch construct that processes the incoming commands after address validation:
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case 'S': // here we have the Set command
if (gethexbyte(RxBuffer[6]) == 0)
{
Output_low(Relay1_Output);
If (Relay1_Status == 1) // only write to EEPROM for changes...
{
Relay1_Status = 0;
//Write_EEPROM(0, Relay1_Status);
}
}
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So, using my example, your node firmware must do the following:
1. Look for a '#' character, and start buffering incoming characters until a <CR> is received, and set a 'valid command' flag.
2. If we have a valid command, look at the address character(s) and compare to the node address.
3. If address match is found, process the command.
4. Loop back to step 1.
Hope this gives you a start!
John |
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vortexe9000
Joined: 07 Jun 2010
Posts: 50
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| dfzerf |
| Posted: Fri May 06, 2011 3:57 am |
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gghnb
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Last edited by vortexe9000 on Sun Feb 19, 2012 7:47 am; edited 3 times in total |
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SherpaDoug
Joined: 07 Sep 2003
Posts: 1640
Location: Cape Cod Mass USA
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| Posted: Fri May 06, 2011 6:23 am |
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First, you should not post the CCS example code on this forum. I think it is a copyright violation somewhere in the fine print.
Next, you should have current limiting resistors for those 3 LEDs called Relay 1, 2, 3.
Third, tell us just what problem you are having. It looks like you have a reasonable start. Most (or at least many) of us don't use simulators so we can't help you with simulation problems. What code have you tried? What did it do or not do that you don't want or want?
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The search for better is endless. Instead simply find very good and get the job done. |
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vortexe9000
Joined: 07 Jun 2010
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| Posted: Fri May 06, 2011 7:16 am |
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vgb
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Last edited by vortexe9000 on Sun Feb 19, 2012 7:30 am; edited 1 time in total |
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ezflyr
Joined: 25 Oct 2010
Posts: 1019
Location: Tewksbury, MA
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| Posted: Fri May 06, 2011 7:58 am |
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Hi,
RS-485 communications is one of those areas where you are going to learn next to nothing by simulating the problem alone. You may get it to "work" on your PC, but it very unlikely that it ever work in the "real world". If your simulator doesn't care about LED current limiting resistors, what else doesn't it care about?
IMHO, the CCS-provide 'RS485.c' code is much more than you need for a simple project like this. It's bloated with lots of conditional code that allows it to work with a wide range of PIC's, and a number of different configurations. For a simple job like you have, it's WAY more trouble than it's worth. If you understand the code intimately, you can clean it up and make it functional, but I don't think you are at that point?
I presented a example of a simple network protocol that would do exactly what you want. I've done lots of similar networks for remote relay control, and environmental sensing, and it works. If you REALLY want to learn something here, I'd recommend scrapping the CCS approach, and creating your own code. It will be simpler, and most important, you will understand it!
As far as your hardware goes, the MAX485 chips all need to have pin 2 and pin 3 connected together. This connection is then wired to a pin on the PIC and will control the direction of data on the network. The compiler will automatically handle control of this connection if you specify an 'Enable=' in your #use rs232 directive.
I know that there is lots of code available on the internet, and elsewhere, but you aren't going to learn a whole lot but simply cutting and pasting and then asking "My code doesn't work, why......?"
Good Luck!
John |
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vortexe9000
Joined: 07 Jun 2010
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| Posted: Fri May 06, 2011 9:28 am |
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cvbhjk
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Last edited by vortexe9000 on Sun Feb 19, 2012 7:31 am; edited 1 time in total |
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Humberto
Joined: 08 Sep 2003
Posts: 1215
Location: Buenos Aires, La Reina del Plata
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| Posted: Fri May 06, 2011 12:38 pm |
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You had been very well guided regarding this point. I want to reinforce the previous comment. For a begginer it is not
easy to take control of the whole RS485 hardware/software system like this. I strongly suggest to do it in real world,
not by simulation, you should start with the minimum hardware (2 PIC + 2 RS485 transceivers) talking in both way,
one each time. You can define your own protocol and control packets and let your basic system to grow including new
nodes and controls.
In this way you will get a `solid' hardware and software as a starting development plataform. Take it easy.
The simulation are good, but for a begginer you loose the feeling of the real world, I mean, if you do not connect a real
resistor between the PIC pin and the LED, for sure you will say "good bye" to the PIC. In the real world, things burn
and die, and this CANT be ignored in your learning stage.
Looking around, you will find many codes that could do what you want, but the best code in this stage is the one that
you can understand and manage. THEN you would learn how to do it solid and efficient.
Write and post your own code. There are many people looking at, and for sure you will receive many helps, more than
if you copy and paste code from somebody.
My 2 cents contribution. Good luck.
Humberto |
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temtronic
Joined: 01 Jul 2010
Posts: 9243
Location: Greensville,Ontario
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| Posted: Fri May 06, 2011 2:21 pm |
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The 'simulator' you're using , doesn't care if you have correctly wired the PIC for a crystal and caps, power supply pins or current limiting resistors.
ANY of those NOT done in the real world will spell disaster. It even doen't warn you that the xmt/rcv pins are wired wrong to the DE-9 connector !
After 40 years of designing with micros(25 with PICs) there isn't ONE simulator that I'd use let alone have any faith in. NONE simulate the real world.Your circuit can have over 40 flaws in it that the 'simulator' will NOT warn you about. Then again you get what you pay for. ISIS/Proteus is free and frankly you couldn't pay me to use it.
Do yourself a HUGE favour. Get rid of it, buy a couple of 'white solderless breadboards', a handful of parts and learn by doing. You'll be much further ahead from dealing with true 'hands on' work. You'll remember the 'little details (xtal caps, pin #s, proper fuse options, etc.) that simulators NEVER care about BUT must be correct for projects to work in the real world! |
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vortexe9000
Joined: 07 Jun 2010
Posts: 50
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| Hi friends ... |
| Posted: Sat May 07, 2011 4:58 am |
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drtze
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Last edited by vortexe9000 on Sun Feb 19, 2012 7:31 am; edited 1 time in total |
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vortexe9000
Joined: 07 Jun 2010
Posts: 50
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| Posted: Sat May 07, 2011 11:28 pm |
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eeferty
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Last edited by vortexe9000 on Sun Feb 19, 2012 7:32 am; edited 1 time in total |
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