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Topic: New Modbusmq project: Testers needed! (Read 6 times) previous topic - next topic

Jason Goldenberg

How do you turn on the debug flag?

Also, how do I setup registers to read and write, can someone post a simple example?

Chuck Adomanis

Does this only work with the "official" ethernet shield.  Seems there are some variants out there now and I would like to buy something to test this with as I have lots of industrial Modbus gear at the office.


Jason Goldenberg

Can someone show me how to setup say 8 modbus words to be read from a "client" and make those control 8 rc servos?

or just any basic modbus tcp program.  I see the library, but i want to get a look at a real example.




I just have updated from Arduino 0018 to 0021, but the modbusmq is not working anymore. Seems to be a problem with the new ethernet library. Any ideas? Is there needed an update of the modbusmq?



I am having the same issue.
Works with 018, but can't even ping the IP when using 021.

Sure would be nice to find a fix for this.


Oct 20, 2010, 04:28 pm Last Edit: Oct 20, 2010, 04:36 pm by Arnonh Reason: 1
I think there is a problem with calling
Code: [Select]
Client client = server.available();
as a global

so change that line to
Code: [Select]
Client client = 0;

please tell me if this helps
for me it seams to fix the problem


It works with:

Client client = 0;

But now I have the same problem with the DEBUG flag. It has to be disabled because if it is enables the Arduino hangs.  

hgs75 do you get it working with debug flag?


No i also couldn't get it to work with the DEBUG flag set.
but i thought it was because i used it with conjunction with i2c
so i just disabled  DEBUG  and moved on


Thanks, changing to "Client client = 0; " worked.

On another note: Is anyone using a simple web interface with Modbusmq, to configure IP, Gateway etc...?

Or have a suggestion as to how to get both Server, Client and different ports working together?


this is a beginning of IP changer over Ethernet but i didn't manage to implement it fully in to the Modbus code
(i have managed to get it to work only by a switch at the beginning of the program before the loop)

Code: [Select]
#include <EEPROM.h>

#include <SPI.h>

#include <Ethernet.h>
#include <Wire.h>

#define maxLength 100

int stringtoint(String &s);

byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
byte ip[] = { 192, 168, 1, 177 };
String inString = "";
int val;
Server server(80);

void setup()
   pinMode(DO_RESET_ETH_SHIELD, OUTPUT);      // sets the digital pin as output
 digitalWrite(DO_RESET_ETH_SHIELD, LOW);
 delay(1000);  //for ethernet chip to reset
 delay(1000);  //for ethernet chip to reset
 if ((EEPROM.read(1) != 0) && (EEPROM.read(1) != 0xFF)){
 ip[0] = EEPROM.read(1);
 ip[1] = EEPROM.read(2);
 ip[2] = EEPROM.read(3);
 ip[3] = EEPROM.read(4);
 Ethernet.begin(mac, ip);
 //BlinkM_stopScript( blinkm_addr );  
void loop()
 int IP1=ip[0];
 int IP2=ip[1];
 int IP3=ip[2];
 int IP4=ip[3];
 Client client = server.available();
 if (client) {
   boolean current_line_is_blank = true;
   while (client.connected()) {
     if (client.available()) {
       char c = client.read();
       if (inString.length() < maxLength) {
         inString += c;
       if (c == '\n' && current_line_is_blank) {

         if (inString.indexOf("?")>0){
          int IP1p = inString.indexOf("IP1");
          int IP2p = inString.indexOf("IP2");
          int IP3p = inString.indexOf("IP3");
          int IP4p = inString.indexOf("IP4");
          int End = inString.indexOf("H");
          String IP1S = inString.substring((IP1p+4), (IP2p-1));
          String IP2S = inString.substring((IP2p+4), (IP3p-1));
          String IP3S = inString.substring((IP3p+4), (IP4p-1));
          String IP4S = inString.substring((IP4p+4), (End-1));
           IP1 = stringtoint(IP1S);
           IP2 = stringtoint(IP2S);
           IP3 = stringtoint(IP3S);
           IP4 = stringtoint(IP4S);
          EEPROM.write(1, IP1);
          EEPROM.write(2, IP2);
          EEPROM.write(3, IP3);
          EEPROM.write(4, IP4);
          int IP1 = atoi(IP1S.toCharArray());
          int IP2 = atoi(IP2S.toCharArray());
          int IP3 = atoi(IP3S.toCharArray());
          int IP4 = atoi(IP4S.toCharArray());
         if (inString.contains("?")) {
          int Pos_r = inString.indexOf("r");
          int Pos_g = inString.indexOf("g");
          int Pos_b = inString.indexOf("b");
          int End = inString.indexOf("H");
          r = atoi(inString.substring((Pos_r+2), (Pos_g-1)));
          g = atoi(inString.substring((Pos_g+2), (Pos_b-1)));
          b = atoi(inString.substring((Pos_b+2), (End-1)));  
          BlinkM_fadeToRGB( blinkm_addr, r, g, b );
         client.println("HTTP/1.1 200 OK");
         client.println("Content-Type: text/html");
         client.println("<h1>Network Settings</h1>");
         client.println("<h3>Saved IP is:  ");
         client.println("<form method=get>IP:.......<input type=text size=2 name=IP1 MAXLENGTH=3><input type=text size=2 name=IP2 MAXLENGTH=3><input type=text size=2 name=IP3 MAXLENGTH=3><input type=text size=2 name=IP4 MAXLENGTH=3>&nbsp;<BR>");      
         //client.println("<form method=get>Subnet:<input type=text size=2 name=S1 MAXLENGTH=3><input type=text size=2 name=S2 MAXLENGTH=3><input type=text size=2 name=S3 MAXLENGTH=3><input type=text size=2 name=S4 MAXLENGTH=3>&nbsp;<BR>");  
         client.println("<input type=submit value=submit></body></html>");
       if (c == '\n') {
         current_line_is_blank = true;
       } else if (c != '\r') {
         current_line_is_blank = false;
   inString = "";

int stringtoint(String &s){
           int n;
          char carray[4];
          s.toCharArray(carray, sizeof(carray));
          n = atoi(carray);



Posted by: chris.moe Posted on: 20.10.2010 at 19:06:02
It works with:

Client client = 0;

But now I have the same problem with the DEBUG flag. It has to be disabled because if it is enables the Arduino hangs.  

hgs75 do you get it working with debug flag?  

Yes, it works with the debug flag, but now I am using an arduino FIO and a WIZ812, use this diagram to make the conections:
The code works fine, I am testing with modscan32, and I still working with the 0018 IDE.  :D


I am trying to use this with IDE 21 and Arduino uno. I have integrated it with the remarks earlier posted, but I can not get it to work. Ping does not work.

When I use another ethernet example it seems to work.

What could be wrong. Could someone post his file that works with IDE21.




Is there a way to add an attachment without using the code insert. The code is rather big as you know Using the code insert would make it unreadable.


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