Fix #211460 reported by Todd Denniston

With TCP, automatic reconnect on error may not be desired.
It's now possible to adjust the error handling mode.

NEWS

@@ -1,3 +1,24 @@
+libmodbus 1.9.x
+- Slave API
+  https://blueprints.launchpad.net/libmodbus/+spec/slave-api
+- Waf build support
+  https://blueprints.launchpad.net/libmodbus/+spec/waf-support
+- MacOS X support by Matthew Butch
+  https://blueprints.launchpad.net/libmodbus/+spec/macosx-support
+- No more glib dependency
+  https://blueprints.launchpad.net/libmodbus/+spec/glib-dependency
+- Fix #159443 reported by Stefan Bisanz
+  Index of incoming data in force multiple coils function
+- Fix #161989 reported by Konstantinos Togias
+  Serial device paths more than 10 chars long (eg. /dev/ttyUSB0) don't
+  fit to modbus_param_t -> device char[11] var.
+- Fix #188189 reported by Chris Hellyar
+  Compute_response_size() no entry for read_input_status()
+- Fix #191039 reported by Todd Denniston
+  modbus.h is not installed at prefix.
+- Fix #211460 reported by Todd Denniston
+  With TCP, automatic reconnect on error may not be desired.
+
 libmodbus 1.2.4 (2008-03-14)
 - Fix #191039 reported by Todd Denniston
   modbus.h is not installed at prefix.
@@ -9,18 +30,18 @@ libmodbus 1.2.3 (2008-02-03)
   Slave address in build_request_packet_tcp() is hardcoded as 0xFF.
 
 libmodbus 1.2.2 (2007-11-12)
-- Fix #161989 (Konstantinos Togias)
+- Fix #161989 reported by Konstantinos Togias
   Serial device paths more than 10 chars long (eg. /dev/ttyUSB0) don't
   fit to modbus_param_t -> device char[11] var.
 - Structure is also bit better 'packed' to conserve memory (see the
   trunk for a real enhancement).
 
 libmodbus 1.2.1 (2007-11-02)
-- Fix #159443 (Stefan Bisanz)
+- Fix #159443 reported by Stefan Bisanz
   Index of incoming data in force multiple coils function
 - Deleted useless code in check_crc16()
 - Untabify source code
-- Changed author's email (Stéphane Raimbault)
+- Changed author's email to Stéphane Raimbault
 
 libmodbus 1.2.0 (2007-05-10)
 - FIX Compilation GCC-4.0

modbus/modbus.c

@@ -148,8 +148,10 @@ static void error_treat(int ret, const char *string, modbus_param_t *mb_param)
         if (mb_param->type_com == RTU) {
                 tcflush(mb_param->fd, TCIOFLUSH);
         } else {
-                modbus_close(mb_param);
-                modbus_connect(mb_param);
+                if (mb_param->error_handling == RECONNECT_ON_ERROR) {
+                        modbus_close(mb_param);
+                        modbus_connect(mb_param);
+                }
         }
 }
 
@@ -1168,6 +1170,28 @@ void modbus_init_tcp(modbus_param_t *mb_param, char *ip, uint16_t port)
         mb_param->type_com = TCP;
         mb_param->header_length = HEADER_LENGTH_TCP;
         mb_param->checksum_size = CHECKSUM_SIZE_TCP;
+        mb_param->error_handling = RECONNECT_ON_ERROR;
+}
+
+/* By default, the error handling mode used is RECONNECT_ON_ERROR.
+
+   With RECONNECT_ON_ERROR, the library will attempt an immediate
+   reconnection which may hang for several seconds if the network to
+   the remote target unit is down.
+
+   With NOP_ON_ERROR, it is expected that the application will
+   check for network error returns and deal with them as necessary.
+
+   This function is only useful in TCP mode. 
+*/
+void modbus_set_error_handling(modbus_param_t *mb_param, error_handling_t error_handling)
+{
+        if (error_handling == RECONNECT_ON_ERROR ||
+            error_handling == NOP_ON_ERROR) {
+                mb_param->error_handling = error_handling;
+        } else {
+                printf("Invalid setting for error handling (not changed)\n");
+        }
 }
 
 

modbus/modbus.h

@@ -108,6 +108,7 @@
 #define MSG_SIZE_UNDEFINED -1
 
 typedef enum { RTU, TCP } type_com_t;
+typedef enum { RECONNECT_ON_ERROR, NOP_ON_ERROR } error_handling_t;
 
 /* This structure is byte-aligned */
 typedef struct {
@@ -148,6 +149,8 @@ typedef struct {
         int header_length;
         /* Checksum size RTU = 2 and TCP = 0 */
         int checksum_size;
+        /* In error_treat with TCP, do a reconnect or just dump the error */
+        error_handling_t error_handling;
 } modbus_param_t;
 
 typedef struct {
@@ -229,6 +232,19 @@ void modbus_init_rtu(modbus_param_t *mb_param, char *device,
 */
 void modbus_init_tcp(modbus_param_t *mb_param, char *ip_address, uint16_t port);
 
+/* By default, the error handling mode used is RECONNECT_ON_ERROR.
+
+   With RECONNECT_ON_ERROR, the library will attempt an immediate
+   reconnection which may hang for several seconds if the network to
+   the remote target unit is down.
+
+   With NOP_ON_ERROR, it is expected that the application will
+   check for network error returns and deal with them as necessary.
+
+   This function is only useful in TCP mode.
+ */
+void modbus_set_error_handling(modbus_param_t *mb_param, error_handling_t error_handling);
+
 /* Sets up a serial port for RTU communications to modbus or a TCP
    connexion */
 int modbus_connect(modbus_param_t *mb_param);