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--- sdk:scripts:modbus-tcp-rtu-gateway [2015/05/05 15:04] – external edit 127.0.0.1
+++ sdk:scripts:modbus-tcp-rtu-gateway [2022/11/08 07:48] (current) – klueppel
@@ Line 1: / Line 1: @@
 ====== SDK Script modbus-tcp-rtu-gateway.are ======
 <code c modbus-tcp-rtu-gateway.are>
-/* DESC: This script can be used to read messages from the serial port.
+/* DESC: This script implements a Modbus TCP RTU gateway
- * Copyright (C) 2015 NetModule AG, Switzerland
+ * Copyright (C) 2015-2016 NetModule AG, Switzerland
  */
+DEVIDX      = 0;
-DEV         = "SERIAL1";
+DEV         = sprintf("SERIAL%d", (DEVIDX + 1));
-TCP_IP      = "192.168.1.1";
 TCP_PORT    = 1502;
+DEBUG       = 0;
 /* check serial port config */
-st = nb_config_get("serial.0.status");
+st = nb_config_get(sprintf("serial.%d.status", DEVIDX));
 if (st != "2") {
-    nb_syslog("Serial port is not enabled for us");
+    nb_syslog("%s is not enabled for us", DEV);
     exit(1);
 }
@@ Line 18: / Line 20: @@
 /* set attributes */
 ret = nb_serial_setattr(DEV, 115200, 8, 1, 0, 0);
 if (ret != 0) {
-    printf("Could not set serial attributes: %i \n",ret);
+    nb_syslog("Could not set serial attributes: %d", ret);
     exit(1);
 }
@@ Line 27: / Line 28: @@
 serial_fd = nb_serial_open(DEV);
 if (serial_fd < 0) {
-    printf("Unable to open %s\n", DEV);
+    nb_syslog("Unable to open %s", DEV);
     exit(1);
 }
 /* register serial_fd as modbus RTU */
-nb_modbus_register(serial_fd, MODBUS_TYPE_RTU);
+if (nb_modbus_register(serial_fd, MODBUS_TYPE_RTU) != 0) {
+    close(serial_fd);
+    nb_syslog("Unable to register as modbus RTU (%s)", nb_modbus_last_error());
+    exit(1);
+}
 sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
 if (sock < 0) {
-    printf("Unable to open socket\n");
+    close(serial_fd);
+    nb_syslog("Unable to open TCP socket");
     exit(1);
 }
@@ Line 42: / Line 48: @@
 ret = bind(sock, TCP_PORT, "");
 if (ret == -1) {
-    printf("Unable to bind port %d\n", port);
+    printf("Unable to bind TCP socket to port %d", TCP_PORT);
+    close(serial_fd);
     close(sock);
     exit(1);
@@ Line 49: / Line 56: @@
 ret = listen(sock, 1);
 if (ret == -1) {
-    printf("Unable to listen\n");
+    nb_syslog("Unable to listen on TCP socket: %d", ret);
+    close(serial_fd);
     close(sock);
     exit(1);
 }
+if (DEBUG == 1) {
+    nb_modbus_set_debug(serial_fd, true);
+}
+printf("Listening for connections on port %d\n", TCP_PORT);
+tcp_client = -1;
+registered = 0;
-printf("Listening for connections on port %d\n", port);
 while (1) {
-    tcp_client = accept(sock);
+    if (tcp_client == -1) {
-    if (tcp_client < 0) {
+        tcp_client = accept(sock);
-        printf("accept failed\n");
+        if (tcp_client < 0) {
-        sleep(1);
+            nb_syslog("Unable to accept new connection");
-        continue;
+            sleep(1);
+            continue;
+        } else {
+            if (DEBUG == 1) {
+                nb_modbus_set_debug(tcp_client, true);
+            }
+        }
     }
-    /* register serial_fd as modbus TCP */
+    /* register client as modbus TCP */
-    if (nb_modbus_register(tcp_client, MODBUS_TYPE_TCP)) {
+    if (registered == 0) {
-        printf("Unable to register client (%s)\n", nb_modbus_last_error());
+       if (nb_modbus_register(tcp_client, MODBUS_TYPE_TCP)) {
-        close(tcp_client);
+            nb_syslog("Unable to register client (%s)", nb_modbus_last_error());
-        continue;
+            close(tcp_client);
+            continue;
+       }
+       registered = 1;
     }
-    /* wait for modbus tcp request */
+    /* wait for a modbus TCP request */
     request = nb_modbus_receive(tcp_client);
-    if (!is_void(request)) {
+    if (is_void(request)) {
-        /* extract payload and forward it to modbus rtu serial_fd */
+        nb_syslog("Unable to receive modbus request (%s)", nb_modbus_last_error());
-        response = nb_modbus_send_raw(serial_fd,
+        nb_modbus_unregister(tcp_client);
-                                      nb_modbus_extract_payload(tcp_client,
+        close(tcp_client);
-                                      request));
+        tcp_client = -1;
-        if (response != NULL) {
+        registered = 0;
-            /* extract payload and send response to modbus tcp */
+        nb_syslog("Disconnected client");
-             nb_modbus_reply_raw_response(tcp_client, request, nb_modbus_extract_payload(serial_fd, response));
+    } else {
+        /* extract payload and forward it to RTU */
+        payload = nb_modbus_extract_payload(tcp_client, request);
+        if (is_void(payload)) {
+            nb_syslog("Unable to extract payload (%s)", nb_modbus_last_error());
         } else {
-            printf("Unable to send response (%s)\n",  nb_modbus_last_error());
+            /* Modbus TCP - RTU must set the slave id */
+       	    ret = nb_modbus_set_slave (serial_fd, payload[0]);
+            if (ret > 0) {
+                nb_syslog("Unable to set modbus slave id");
+                break;
+            }
+            response = nb_modbus_send_raw(serial_fd, payload);
+            if (is_void(response)) {
+                nb_syslog("Unable to send modbus response (%s)", nb_modbus_last_error());
+            } else {
+                /* extract payload and send response to modbus tcp */
+                payload = nb_modbus_extract_payload(serial_fd, response);
+                if (is_void(payload)) {
+                    nb_syslog("Unable to extract payload (%s)", nb_modbus_last_error());
+                } else {
+                    nb_modbus_reply_raw_response(tcp_client, request, payload);
+                }
+            }
         }
-    } else {
-        printf("Unable to receive request (%s)\n",  nb_modbus_last_error());
     }
+}
+if (tcp_client > -1) {
+    if (registered) {
+        nb_modbus_unregister(tcp_client);
+    }
+    close(tcp_client);
 }
 nb_modbus_unregister(serial_fd);
-nb_modbus_unregister(tcp_client);
 close(serial_fd);
-close(tcp_client);
 exit(0);
 </code>

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