modbus plugin: Add support for libmodbus version 2.9.2.

This is the current "unstable" release. Hopefully the API won't
change too much in the future. All in all this new interface is
much nicer. The stable ("legacy") version of libmodbus is still
supported through preprocessor macros.

diff --git a/configure.in b/configure.in
index c2ddaf0..69bbfe1 100644 (file)
--- a/configure.in
+++ b/configure.in
@@ -2104,9 +2104,9 @@ then
        CPPFLAGS="$CPPFLAGS $with_libmodbus_cflags"
        LDFLAGS="$LDFLAGS $with_libmodbus_libs"
 
-       AC_CHECK_LIB(modbus, modbus_init_tcp,
+       AC_CHECK_LIB(modbus, modbus_connect,
                     [with_libmodbus="yes"],
-                    [with_libmodbus="no (symbol modbus_init_tcp not found)"])
+                    [with_libmodbus="no (symbol modbus_connect not found)"])
 
        CPPFLAGS="$SAVE_CPPFLAGS"
        LDFLAGS="$SAVE_LDFLAGS"

diff --git a/src/modbus.c b/src/modbus.c
index 6a753e1..17396ed 100644 (file)
--- a/src/modbus.c
+++ b/src/modbus.c
@@ -28,6 +28,13 @@
 
 #include <modbus/modbus.h>
 
+#ifndef LIBMODBUS_VERSION_CHECK
+/* Assume version 2.0.3 */
+# define LEGACY_LIBMODBUS 1
+#else
+/* Assume version 2.9.2 */
+#endif
+
 #ifndef MODBUS_TCP_DEFAULT_PORT
 # ifdef MODBUS_TCP_PORT
 #  define MODBUS_TCP_DEFAULT_PORT MODBUS_TCP_PORT
@@ -99,7 +106,11 @@ struct mb_host_s /* {{{ */
   mb_slave_t *slaves;
   size_t slaves_num;
 
+#if LEGACY_LIBMODBUS
   modbus_param_t connection;
+#else
+  modbus_t *connection;
+#endif
   _Bool is_connected;
   _Bool have_reconnected;
 }; /* }}} */
@@ -265,6 +276,8 @@ static float mb_register_to_float (uint16_t hi, uint16_t lo) /* {{{ */
   return (conv.f);
 } /* }}} float mb_register_to_float */
 
+#if LEGACY_LIBMODBUS
+/* Version 2.0.3 */
 static int mb_init_connection (mb_host_t *host) /* {{{ */
 {
   int status;
@@ -306,6 +319,57 @@ static int mb_init_connection (mb_host_t *host) /* {{{ */
   host->have_reconnected = 1;
   return (0);
 } /* }}} int mb_init_connection */
+/* #endif LEGACY_LIBMODBUS */
+
+#else /* if !LEGACY_LIBMODBUS */
+/* Version 2.9.2 */
+static int mb_init_connection (mb_host_t *host) /* {{{ */
+{
+  int status;
+
+  if (host == NULL)
+    return (EINVAL);
+
+  if (host->connection != NULL)
+    return (0);
+
+  /* Only reconnect once per interval. */
+  if (host->have_reconnected)
+    return (-1);
+
+  if ((host->port < 1) || (host->port > 65535))
+    host->port = MODBUS_TCP_DEFAULT_PORT;
+
+  DEBUG ("Modbus plugin: Trying to connect to \"%s\", port %i.",
+      host->node, host->port);
+
+  host->connection = modbus_new_tcp (host->node, host->port);
+  if (host->connection == NULL)
+  {
+    host->have_reconnected = 1;
+    ERROR ("Modbus plugin: Creating new Modbus/TCP object failed.");
+    return (-1);
+  }
+
+  modbus_set_debug (host->connection, 1);
+
+  /* We'll do the error handling ourselves. */
+  modbus_set_error_recovery (host->connection, 0);
+
+  status = modbus_connect (host->connection);
+  if (status != 0)
+  {
+    ERROR ("Modbus plugin: modbus_connect (%s, %i) failed with status %i.",
+        host->node, host->port, status);
+    modbus_free (host->connection);
+    host->connection = NULL;
+    return (status);
+  }
+
+  host->have_reconnected = 1;
+  return (0);
+} /* }}} int mb_init_connection */
+#endif /* !LEGACY_LIBMODBUS */
 
 #define CAST_TO_VALUE_T(ds,vt,raw) do { \
   if ((ds)->ds[0].type == DS_TYPE_COUNTER) \
@@ -360,22 +424,46 @@ static int mb_read_data (mb_host_t *host, mb_slave_t *slave, /* {{{ */
   else
     values_num = 1;
 
+#if LEGACY_LIBMODBUS
+  /* Version 2.0.3: Pass the connection struct as a pointer and pass the slave
+   * id to each call of "read_holding_registers". */
+# define modbus_read_registers(ctx, addr, nb, dest) \
+  read_holding_registers (&(ctx), slave->id, (addr), (nb), (dest))
+#else /* if !LEGACY_LIBMODBUS */
+  /* Version 2.9.2: Set the slave id once before querying the registers. */
+  status = modbus_set_slave (host->connection, slave->id);
+  if (status != 0)
+  {
+    ERROR ("Modbus plugin: modbus_set_slave (%i) failed with status %i.",
+        slave->id, status);
+    return (-1);
+  }
+#endif
+
   for (i = 0; i < 2; i++)
   {
-    status = read_holding_registers (&host->connection,
-        /* slave = */ slave->id, /* start_addr = */ data->register_base,
+    status = modbus_read_registers (host->connection,
+        /* start_addr = */ data->register_base,
         /* num_registers = */ values_num, /* buffer = */ values);
     if (status > 0)
       break;
 
     if (host->is_connected)
+    {
+#if LEGACY_LIBMODBUS
       modbus_close (&host->connection);
-    host->is_connected = 0;
+      host->is_connected = 0;
+#else
+      modbus_close (host->connection);
+      modbus_free (host->connection);
+      host->connection = NULL;
+#endif
+    }
 
     /* If we already tried reconnecting this round, give up. */
     if (host->have_reconnected)
     {
-      ERROR ("Modbus plugin: read_holding_registers (%s) failed. "
+      ERROR ("Modbus plugin: modbus_read_registers (%s) failed. "
           "Reconnecting has already been tried. Giving up.", host->host);
       return (-1);
     }
@@ -385,7 +473,7 @@ static int mb_read_data (mb_host_t *host, mb_slave_t *slave, /* {{{ */
     status = mb_init_connection (host);
     if (status != 0)
     {
-      ERROR ("Modbus plugin: read_holding_registers (%s) failed. "
+      ERROR ("Modbus plugin: modbus_read_registers (%s) failed. "
           "While trying to reconnect, connecting to \"%s\" failed. "
           "Giving up.",
           host->host, host->node);
@@ -399,7 +487,7 @@ static int mb_read_data (mb_host_t *host, mb_slave_t *slave, /* {{{ */
   } /* for (i = 0, 1) */
 
   DEBUG ("Modbus plugin: mb_read_data: Success! "
-      "read_holding_registers returned with status %i.", status);
+      "modbus_read_registers returned with status %i.", status);
 
   if (data->register_type == REG_TYPE_FLOAT)
   {