Merge branch 'modbus_watchdog'

README.md

@@ -141,7 +141,16 @@ Modbus network configuration parameters are listed below:
 
   Same as delay_before_first_command, but a delay is applied to every modbus command sent on this network.
 
-* RTU device settings
+* **read_retries** (optional, default 1)
+
+  A number of retries after a modbus read command fails.
+
+* **write_retries** (optional, default 2)
+
+  A number of retries after a modbus write command fails.
+
+* **RTU device settings**
+
   For details, see modbus_new_rtu(3)
 
   * **device** (required)
@@ -176,7 +185,7 @@ Modbus network configuration parameters are listed below:
 
     modbus Request To Send delay period in microseconds. See modbus_rtu_set_rts_delay(3)
 
-* TCP/IP device settings
+* **TCP/IP device settings**
 
   * **address**
 
@@ -186,6 +195,16 @@ Modbus network configuration parameters are listed below:
 
     TCP port of a device
 
+* **watchdog** (optional)    
+
+  An optional configuration section for modbus connection watchdog. Watchdog monitors modbus command errors. If there is no successful command execution in *watch_period*, then it restarts the modbus connection.
+
+  Additionally for RTU network the *device* path is checked on the first error and then in small (300ms) time periods. If modbus RTU device is unplugged, then connection is restarted.
+
+  * **watch_period** (optional, timespan, default=10s)
+    
+  The amount of time after which the connection should be reestablished if there has been no successful execution of a modbus command.
+
 * **slaves** (optional)
   An optional slave list with modbus specific configuration like register groups to poll (see poll groups below) and timing constraints
 
@@ -201,6 +220,14 @@ Modbus network configuration parameters are listed below:
 
       Same as global *delay_before_command* but applies to this slave only.
 
+  * **read_retries** (optional)
+
+    A number of retries after a modbus read command to this slave fails. Uses the global *read_retries* if not defined.
+
+  * **write_retries** (optional)
+
+    A number of retries after a modbus write command to this slave fails. Uses the global *write_retries* if not defined.
+
   * **poll_groups** (optional)
 
       An optional list of modbus register address ranges that will be polled with a single modbus_read_registers(3) call.

libmodmqttsrv/CMakeLists.txt

@@ -31,6 +31,8 @@ add_library(modmqttsrv
     modbus_thread.hpp
     modbus_types.cpp
     modbus_types.hpp
+    modbus_watchdog.cpp
+    modbus_watchdog.hpp
     modmqtt.cpp 
     modmqtt.hpp 
     mosquitto.cpp

libmodmqttsrv/config.cpp

@@ -7,7 +7,7 @@ namespace modmqttd {
 boost::log::sources::severity_logger<Log::severity> ModbusNetworkConfig::log;
 
 #if __cplusplus < 201703L
-    constexpr std::chrono::milliseconds ModbusNetworkConfig::MAX_RESPONSE_TIMEOUT;
+constexpr std::chrono::milliseconds ModbusNetworkConfig::MAX_RESPONSE_TIMEOUT;
 #endif
 
 ConfigurationException::ConfigurationException(const YAML::Mark& mark, const char* what) {
@@ -43,6 +43,9 @@ ModbusNetworkConfig::ModbusNetworkConfig(const YAML::Node& source) {
     ConfigTools::readOptionalValue<std::chrono::milliseconds>(this->mDelayBeforeCommand, source, "delay_before_command");
     ConfigTools::readOptionalValue<std::chrono::milliseconds>(this->mDelayBeforeFirstCommand, source, "delay_before_first_command");
 
+    ConfigTools::readOptionalValue<unsigned short>(this->mMaxWriteRetryCount, source, "write_retries");
+    ConfigTools::readOptionalValue<unsigned short>(this->mMaxReadRetryCount, source, "read_retries");
+
 
     if (source["device"]) {
         mType = Type::RTU;
@@ -54,13 +57,19 @@ ModbusNetworkConfig::ModbusNetworkConfig(const YAML::Node& source) {
         ConfigTools::readOptionalValue<RtuSerialMode>(this->mRtuSerialMode, source, "rtu_serial_mode");
         ConfigTools::readOptionalValue<RtuRtsMode>(this->mRtsMode, source, "rtu_rts_mode");
         ConfigTools::readOptionalValue<int>(this->mRtsDelayUs, source, "rtu_rts_delay_us");
+
+        mWatchdogConfig.mDevicePath = mDevice;
     } else if (source["address"]) {
         mType = Type::TCPIP;
         mAddress = ConfigTools::readRequiredString(source, "address");
         mPort = ConfigTools::readRequiredValue<int>(source, "port");
     } else {
         throw ConfigurationException(source.Mark(), "Cannot determine modbus network type: missing 'device' or 'address'");
     }
+
+    if (source["watchdog"]) {
+        ConfigTools::readOptionalValue<std::chrono::milliseconds>(this->mWatchdogConfig.mWatchPeriod, source["watchdog"], "watch_period");
+    }
 }
 
 MqttBrokerConfig::MqttBrokerConfig(const YAML::Node& source) {

libmodmqttsrv/config.hpp

@@ -75,6 +75,11 @@ class ConfigTools {
         }
 };
 
+class ModbusWatchdogConfig {
+    public:
+        std::chrono::milliseconds mWatchPeriod = std::chrono::seconds(10);
+        std::string mDevicePath;
+};
 
 class ModbusNetworkConfig {
     static constexpr std::chrono::milliseconds MAX_RESPONSE_TIMEOUT = std::chrono::milliseconds(999);
@@ -106,9 +111,14 @@ class ModbusNetworkConfig {
         std::string mName = "";
         std::chrono::milliseconds mResponseTimeout = std::chrono::milliseconds(500);
         std::chrono::milliseconds mResponseDataTimeout = std::chrono::seconds(0);
+
         std::chrono::milliseconds mDelayBeforeCommand = std::chrono::seconds(0);
         std::chrono::milliseconds mDelayBeforeFirstCommand = std::chrono::seconds(0);
 
+        unsigned short mMaxWriteRetryCount = 2;
+        unsigned short mMaxReadRetryCount = 1;
+
+
         //RTU only
         std::string mDevice = "";
         int mBaud = 0;
@@ -122,6 +132,8 @@ class ModbusNetworkConfig {
         //TCP only
         std::string mAddress = "";
         int mPort = 0;
+
+        ModbusWatchdogConfig mWatchdogConfig;
 };
 
 class MqttBrokerConfig {

libmodmqttsrv/modbus_context.cpp

@@ -117,6 +117,7 @@ ModbusContext::connect() {
 void
 ModbusContext::disconnect() {
     modbus_close(mCtx);
+    mIsConnected = false;
 }
 
 std::vector<uint16_t>