Improved compatibility

External libraries have been replaced to improve compatibility. Sketch is now compatible with Arduino Nano, Uno and Mega. Ethernet chips W5100, W5200 and W5500.

Author: budulinek

README.md

@@ -43,11 +43,11 @@ Screenshots of the web interface:
 ## How can I build it myself?
 Get the hardware. Cheap clones from China are sufficient:
 
-* Arduino (Nano, Uno, possibly other)
-* W5500-based Ethernet shield (for Nano, I recommend W5500 Ethernet Shield from RobotDyn)
+* Arduino Nano, Uno or Mega (and possibly other)
+* W5100, W5200 or W5500 based Ethernet shield (for Nano, I recommend W5500 Ethernet Shield from RobotDyn)
 * MAX485 module
 
-Connect the hardware:
+Connect the hardware (on Nano and Uno, the sketch uses HW Serial, on Mega you have to configure Serial in ADVANCED SETTINGS in the sketch):
 
 * Arduino <-> MAX485
 
@@ -57,7 +57,7 @@ Connect the hardware:
 
 * Pin 6 <-> DE,RE
 
-Download this repository (all *.ino files) and open arduino-modbus-rtu-tcp-gateway.ino in Arduino IDE. Download all required libraries (some of them are available in "library manager", other have to be manually downloaded from github). If you want, you can check the default factory settings (can be later changed via web interface) and advanced settings (can only be changed in sketch). Compile and upload your program to Arduino. Connect your Arduino to ethernet, connect your Modbus RTU slaves to MAX485 module. Use your web browser to access the web interface on default IP  http://192.168.1.254   Enjoy :-)
+Download this repository (all *.ino files) and open arduino-modbus-rtu-tcp-gateway.ino in Arduino IDE. Download all required libraries (both are available in "library manager"). If you want, you can check the default factory settings (can be later changed via web interface) and advanced settings (can only be changed in sketch). Compile and upload your program to Arduino. Connect your Arduino to ethernet, connect your Modbus RTU slaves to MAX485 module. Use your web browser to access the web interface on default IP  http://192.168.1.254   Enjoy :-)
 
 ## Where can I learn more about Modbus protocols?
 
@@ -74,15 +74,32 @@ The key to success is:
 
 * use StreamLib https://github.com/jandrassy/StreamLib
 * use F macros for your HTML code
-* for W5500 ethernet modules, use Ethernet3 https://github.com/sstaub/Ethernet3
+* use for() loop for repetitive code
 * use POST method (rather than GET) for your webforms, see this tutorial https://werner.rothschopf.net/202003_arduino_webserver_post_en.htm
 
 Big thanks to the authors of these libraries and tutorials!
 
-## Background
+## Limitations
 
-This project started as a simple "playground" where I learned things. However, it evolved into more serious project: Modbus gateway in full compliance with Modbus standards. Later on, web interface was added as a demonstration of what a simple Arduino Nano is capable of. 
+#### Portability
 
-Not everything could fit into the limited flash memory of Arduino Nano / Uno. The DHCP client within a ethernet library consumes too much memory. The code for automatic IP address is in the sketch but disabled by default. If you want to use auto IP functionality, you have to use something bigger (such as Arduino Mega) and uncomment #define ENABLE_DHCP. After that, new "Auto IP" setting will appear in the IP settings web interface.
+The code was tested on Arduino Nano, Uno and Mega, ethernet chips W5100 and W5500. It may work on other platforms, but:
+
+* The pseudorandom generator (for random MAC) is seeded through watch dog timer interrupt - this will work only on Arduino (credits to https://sites.google.com/site/astudyofentropy/project-definition/timer-jitter-entropy-sources/entropy-library/arduino-random-seed)
+* The restart function will also work only on Arduino.
+
+#### Ethernet socket
+
+The default Ethernet.h library determines MAX_SOCK_NUM by microcontroller RAM (not by Ethernet chip type). So if you use W5500 (which has 8 sockets available) on Arduino Nano, only 4 sockets will be used. If you want to force the library to use 8 sockets, edit https://github.com/arduino-libraries/Ethernet/blob/master/src/Ethernet.h#L36 
+
+#### Memory
+
+Not everything could fit into the limited flash memory of Arduino Nano / Uno. If you have a microcontroller with more memory (such as Mega), you can enable extra features in the main sketch by uncommenting:
+
+* #define ENABLE_DHCP will allow you to set "Auto IP" via DHCP in the IP settings web interface. Leased IP is automatically renewed.
 
 <img src="/pics/modbus6.png" alt="06" style="zoom:100%;" />
+
+* #define ENABLE_EXTRA_DIAG  shows extra info on "Current status" page: per socket diagnostics, run time counter.
+
+<img src="/pics/modbus1x.png" alt="01x" style="zoom:100%;" />

arduino-modbus-rtu-tcp-gateway/01-interfaces.ino

@@ -13,18 +13,29 @@
    resetFunc
    - well... resets Arduino
 
+   maintainDhcp()
+   - maintain DHCP lease
+   
    maintainUptime
    - maintains up time in case of millis() overflow
 
    maintainCounters
    - synchronizes roll-over of data counters to zero
 
+   CreateTrulyRandomSeed
+   - seed pseudorandom generator using  watch dog timer interrupt (works only on AVR)
+   - see https://sites.google.com/site/astudyofentropy/project-definition/timer-jitter-entropy-sources/entropy-library/arduino-random-seed
+
+   generateMac()
+   - generate random MAC using pseudo random generator (faster and than build-in random())
+
    + preprocessor code for identifying microcontroller board
 
    ***************************************************************** */
 
+
 void startSerial() {
-  Serial.begin(localConfig.baud, localConfig.serialConfig);
+  mySerial.begin(localConfig.baud, localConfig.serialConfig);
   // Calculate Modbus RTU character timeout and frame delay
   byte bits =                                         // number of bits per character (11 in default Modbus RTU settings)
     1 +                                               // start bit
@@ -40,31 +51,56 @@ void startSerial() {
     charTimeout = 750;
     frameDelay = 1750;
   }
-  pinMode(SerialTxControl, OUTPUT);
-  digitalWrite(SerialTxControl, RS485Receive);  // Init Transceiver
+  pinMode(rs485ControlPin, OUTPUT);
+  digitalWrite(rs485ControlPin, RS485_RECEIVE);  // Init Transceiver
 }
 
 void startEthernet() {
-  Ethernet.setRstPin(ethResetPin);
+  if (ethResetPin != 0) {
+    pinMode(ethResetPin, OUTPUT);
+    digitalWrite(ethResetPin, LOW);
+    delay(25);
+    digitalWrite(ethResetPin, HIGH);
+    delay(500);
+  }
 #ifdef ENABLE_DHCP
-  if (!localConfig.enableDhcp || !Ethernet.begin(localConfig.mac)) {
-    Ethernet.begin(localConfig.mac, localConfig.ip, localConfig.subnet, localConfig.gateway, localConfig.dns);
+  if (localConfig.enableDhcp) {
+    dhcpSuccess = Ethernet.begin(localConfig.mac);
+  }
+  if (!localConfig.enableDhcp || dhcpSuccess == false) {
+    Ethernet.begin(localConfig.mac, localConfig.ip, localConfig.dns, localConfig.gateway, localConfig.subnet);
   }
 #else /* ENABLE_DHCP */
-  Ethernet.begin(localConfig.mac, localConfig.ip, localConfig.subnet, localConfig.gateway, localConfig.dns);
-  localConfig.enableDhcp = false;                 // Ensure Dhcp is disabled in config
+  Ethernet.begin(localConfig.mac, localConfig.ip, localConfig.dns, localConfig.gateway, localConfig.subnet);
+  localConfig.enableDhcp = false;                 // Make sure Dhcp is disabled in config
 #endif /* ENABLE_DHCP */
   modbusServer = EthernetServer(localConfig.tcpPort);
   webServer = EthernetServer(localConfig.webPort);
   Udp.begin(localConfig.udpPort);
   modbusServer.begin();
   webServer.begin();
+  // Ethernet library determines MAX_SOCK_NUM by Microcontroller RAM (not by Ethernet chip type).
+  // Therefore, for Arduino Mega + W5100, MAX_SOCK_NUM is wrongly set to 8
+  if (Ethernet.hardwareStatus() == EthernetW5100) {
+    maxSockNum = 4;
+  }
   dbg(F("[arduino] Server available at http://"));
   dbgln(Ethernet.localIP());
 }
 
 void(* resetFunc) (void) = 0;   //declare reset function at address 0
 
+void maintainDhcp()
+{
+  if (localConfig.enableDhcp && dhcpSuccess == true) {      // only call maintain if initial DHCP request by startEthernet was successfull
+    uint8_t maintainResult = Ethernet.maintain();
+    if (maintainResult == 1 || maintainResult == 3) {    // renew failed or rebind failed
+      dhcpSuccess = false;
+      startEthernet();      // another DHCP request, fallback to static IP
+    }
+  }
+}
+
 void maintainUptime()
 {
   unsigned long milliseconds = millis();
@@ -82,15 +118,65 @@ void maintainUptime()
 
 void maintainCounters()
 {
-  // synchronize roll-over of data counters to zero, at 0xFFFFF000
-  if (serialTxCount > 0xFFFFF000 || serialRxCount > 0xFFFFF000 || ethTxCount > 0xFFFFF000 || ethRxCount > 0xFFFFF000) {
+  // synchronize roll-over of data counters to zero, at 0xFFFFFF00 or 0xFF00 respectively
+#ifdef ENABLE_EXTRA_DIAG
+  const unsigned long rollover = 0xFFFFFF00;
+#else
+  const unsigned int rollover = 0xFF00;
+#endif /* ENABLE_EXTRA_DIAG */
+  if (serialTxCount > rollover || serialRxCount > rollover || ethTxCount > rollover || ethRxCount > rollover) {
     serialRxCount = 0;
     serialTxCount = 0;
     ethRxCount = 0;
     ethTxCount = 0;
   }
 }
 
+
+void generateMac()
+{
+  // Marsaglia algorithm from https://github.com/RobTillaart/randomHelpers
+  seed1 = 36969L * (seed1 & 65535L) + (seed1 >> 16);
+  seed2 = 18000L * (seed2 & 65535L) + (seed2 >> 16);
+  uint32_t randomBuffer = (seed1 << 16) + seed2;  /* 32-bit random */
+
+  for (byte i = 0; i < 3; i++) {
+    localConfig.mac[i + 3] = randomBuffer & 0xFF;
+    randomBuffer >>= 8;
+  }
+}
+
+void CreateTrulyRandomSeed()
+{
+  seed1 = 0;
+  nrot = 32; // Must be at least 4, but more increased the uniformity of the produced
+  // seeds entropy.
+
+  // The following five lines of code turn on the watch dog timer interrupt to create
+  // the seed value
+  cli();
+  MCUSR = 0;
+  _WD_CONTROL_REG |= (1 << _WD_CHANGE_BIT) | (1 << WDE);
+  _WD_CONTROL_REG = (1 << WDIE);
+  sei();
+
+  while (nrot > 0);  // wait here until seed is created
+
+  // The following five lines turn off the watch dog timer interrupt
+  cli();
+  MCUSR = 0;
+  _WD_CONTROL_REG |= (1 << _WD_CHANGE_BIT) | (0 << WDE);
+  _WD_CONTROL_REG = (0 << WDIE);
+  sei();
+}
+
+ISR(WDT_vect)
+{
+  nrot--;
+  seed1 = seed1 << 8;
+  seed1 = seed1 ^ TCNT1L;
+}
+
 // Board definitions
 #if defined(TEENSYDUINO)
 

arduino-modbus-rtu-tcp-gateway/02-modbus-tcp.ino

@@ -21,11 +21,15 @@
 
    deleteRequest
    - deletes requests from queue
-   
-   ***************************************************************** */
 
+   getSlaveResponding, setSlaveResponding
+   - read from and write to bool array
+
+   ***************************************************************** */
 
-BitBool<maxSlaves> slavesResponding;
+// bool array for storing Modbus RTU status (responging or not responding). Array index corresponds to slave address.
+uint8_t slavesResponding[(maxSlaves + 1 + 7) / 8];
+uint8_t  masks[8] = {1, 2, 4, 8, 16, 32, 64, 128};
 
 typedef struct {
   byte tid[2];            // MBAP Transaction ID
@@ -43,7 +47,7 @@ CircularBuffer<byte, reqQueueCount> queueRetries;              // queue of retry
 
 void recvUdp()
 {
-  int packetSize = Udp.parsePacket();
+  unsigned int packetSize = Udp.parsePacket();
   if (packetSize)
   {
     ethRxCount += packetSize;
@@ -53,18 +57,18 @@ void recvUdp()
     Udp.read(udpInBuffer, sizeof(udpInBuffer));
     Udp.flush();
 
-    int errorCode = checkRequest(udpInBuffer, packetSize);
+    byte errorCode = checkRequest(udpInBuffer, packetSize);
     byte pduStart;        // first byte of Protocol Data Unit (i.e. Function code)
     if (localConfig.enableRtuOverTcp) pduStart = 1;   // In Modbus RTU, Function code is second byte (after address)
     else pduStart = 7;            // In Modbus TCP/UDP, Function code is 8th byte (after address)
     if (errorCode == 0) {
       // Store in request queue: 2 bytes MBAP Transaction ID (ignored in Modbus RTU over TCP); MBAP Unit ID (address); PDUlen (func + data);remote IP; remote port; TCP client Number (socket) - 0xFF for UDP
-      queueHeaders.push(header {{udpInBuffer[0], udpInBuffer[1]}, udpInBuffer[pduStart - 1], packetSize - pduStart, Udp.remoteIP(), Udp.remotePort(), UDP_REQUEST});
+      queueHeaders.push(header {{udpInBuffer[0], udpInBuffer[1]}, udpInBuffer[pduStart - 1], (byte)(packetSize - pduStart), Udp.remoteIP(), Udp.remotePort(), UDP_REQUEST});
       queueRetries.push(0);
-      for (byte i = 0; i < packetSize - pduStart; i++) {
+      for (byte i = 0; i < (byte)(packetSize - pduStart); i++) {
         queuePDUs.push(udpInBuffer[i + pduStart]);
       }
-    } else if (errorCode > 0) {
+    } else if (errorCode != 0xFF) {
       // send back message with error code
       Udp.beginPacket(Udp.remoteIP(), Udp.remotePort());
       if (!localConfig.enableRtuOverTcp) {
@@ -94,25 +98,25 @@ void recvTcp()
 {
   EthernetClient client = modbusServer.available();
   if (client) {
-    int packetSize = client.available();
+    unsigned int packetSize = client.available();
     ethRxCount += packetSize;
     byte tcpInBuffer[modbusSize + 4];          // Modbus TCP frame is 4 bytes longer than Modbus RTU frame
     // Modbus TCP/UDP frame: [0][1] transaction ID, [2][3] protocol ID, [4][5] length and [6] unit ID (address).....
     // Modbus RTU frame: [0] address.....
     client.read(tcpInBuffer, sizeof(tcpInBuffer));
     client.flush();
-    int errorCode = checkRequest(tcpInBuffer, packetSize);
+    byte errorCode = checkRequest(tcpInBuffer, packetSize);
     byte pduStart;        // first byte of Protocol Data Unit (i.e. Function code)
     if (localConfig.enableRtuOverTcp) pduStart = 1;   // In Modbus RTU, Function code is second byte (after address)
     else pduStart = 7;            // In Modbus TCP/UDP, Function code is 8th byte (after address)
     if (errorCode == 0) {
       // Store in request queue: 2 bytes MBAP Transaction ID (ignored in Modbus RTU over TCP); MBAP Unit ID (address); PDUlen (func + data);remote IP; remote port; TCP client Number (socket) - 0xFF for UDP
-      queueHeaders.push(header {{tcpInBuffer[0], tcpInBuffer[1]}, tcpInBuffer[pduStart - 1], packetSize - pduStart, {}, 0, client.getSocketNumber()});
+      queueHeaders.push(header {{tcpInBuffer[0], tcpInBuffer[1]}, tcpInBuffer[pduStart - 1], (byte)(packetSize - pduStart), {}, 0, client.getSocketNumber()});
       queueRetries.push(0);
       for (byte i = 0; i < packetSize - pduStart; i++) {
         queuePDUs.push(tcpInBuffer[i + pduStart]);
       }
-    } else if (errorCode > 0) {
+    } else if (errorCode != 0xFF) {
       // send back message with error code
       if (!localConfig.enableRtuOverTcp) {
         client.write(tcpInBuffer, 5);
@@ -155,14 +159,14 @@ void processRequests()
     if (!queueHeaders.isEmpty()) {
       boolean queueHasRespondingSlaves;               // true if  queue holds at least one request to responding slaves
       for (byte i = 0; i < queueHeaders.size(); i++) {
-        if (slavesResponding[queueHeaders[i].uid] == true) {
+        if (getSlaveResponding(queueHeaders[i].uid) == true) {
           queueHasRespondingSlaves = true;
           break;
         } else {
           queueHasRespondingSlaves = false;
         }
       }
-      while (queueHasRespondingSlaves == true && slavesResponding[queueHeaders.first().uid] == false) {
+      while (queueHasRespondingSlaves == true && getSlaveResponding(queueHeaders.first().uid) == false) {
         // move requests to non responding slaves to the tail of the queue
         for (byte i = 0; i < queueHeaders.first().PDUlen; i++) {
           queuePDUs.push(queuePDUs.shift());
@@ -175,22 +179,21 @@ void processRequests()
   }
 }
 
-int checkRequest(byte buffer[], int bufferSize) {
+byte checkRequest(byte buffer[], unsigned int bufferSize) {
   byte address;
   if (localConfig.enableRtuOverTcp) address = buffer[0];
   else address = buffer[6];
 
   if (localConfig.enableRtuOverTcp) {   // check CRC for Modbus RTU over TCP/UDP
     if (checkCRC(buffer, bufferSize) == false) {
-      return -1;                         // reject: do nothing and return no error code
+      return 0xFF;                         // reject: do nothing and return no error code
     }
   } else {                  // check MBAP header structure for Modbus TCP/UDP
-    if (buffer[2] != 0x00 || buffer[3] != 0x00 || buffer[4] != 0x00 || buffer[5] + 6 != bufferSize) {
-      return -1;                         // reject: do nothing and return no error code
+    if (buffer[2] != 0x00 || buffer[3] != 0x00 || buffer[4] != 0x00 || buffer[5] != bufferSize - 6) {
+      return 0xFF;                         // reject: do nothing and return no error code
     }
   }
-
-  if (queueHeaders.isEmpty() == false && slavesResponding[address] == false) {                       // allow only one request to non responding slaves
+  if (queueHeaders.isEmpty() == false && getSlaveResponding(address) == false) {                       // allow only one request to non responding slaves
     for (byte j = queueHeaders.size(); j > 0 ; j--) {     // start searching from tail because requests to non-responsive slaves are usually towards the tail of the queue
       if (queueHeaders[j - 1].uid == address) {
         return 0x0B;                   // return modbus error 11 (Gateway Target Device Failed to Respond) - usually means that target device (address) is not present
@@ -213,3 +216,18 @@ void deleteRequest()        // delete request from queue
   queueHeaders.shift();
   queueRetries.shift();
 }
+
+
+bool getSlaveResponding(const uint8_t index)
+{
+  if (index >= maxSlaves) return false;     // error
+  return (slavesResponding[index / 8] & masks[index & 7]) > 0;
+}
+
+
+void setSlaveResponding(const uint8_t index, const bool value)
+{
+  if (index >= maxSlaves) return;     // error
+  if (value == 0) slavesResponding[index / 8] &= ~masks[index & 7];
+  else slavesResponding[index / 8] |= masks[index & 7];
+}