diff --git a/.gitignore b/.gitignore
index a18ea62..d5f7474 100644
--- a/.gitignore
+++ b/.gitignore
@@ -8,4 +8,5 @@
 .cproject
 .pydevproject
 /build
+/build-arm
 build.sh
\ No newline at end of file
diff --git a/conf/mbusd.conf.example b/conf/mbusd.conf.example
index 2cde560..22cf67b 100644
--- a/conf/mbusd.conf.example
+++ b/conf/mbusd.conf.example
@@ -18,12 +18,43 @@ mode = 8n1
 # Enable RS-485 support for given serial port device (Linux only)
 # enable_rs485 = no
 
-# RS-485 data direction control type (addc, rts, sysfs_0, sysfs_1)
+# RS-485 data direction control type (addc, rts, sysfs_0, sysfs_1, ioctl)
 trx_control = addc
 
 # Sysfs file to use to control data direction
 # trx_sysfile =
 
+# Example IOCTL configuration
+
+#trx_control = ioctl
+#trx_sysfile = /dev/gpio_ctl
+
+# IOCTL request number
+
+#trx_ioctl_req = 0x40080004
+
+# IOCTL argument type (long, struct)
+
+# "long" argument example
+
+#trx_ioctl_arg_type = long
+
+# 1 when RTS set, 0 when clear
+# rts_inv for inverse
+#trx_ioctl_val = rts
+
+
+# "struct" argument example
+
+#trx_ioctl_arg_type = struct
+
+#trx_ioctl_val_1 = 0
+
+# 1 when RTS set, 0 when clear
+# rts_inv for inverse
+#trx_ioctl_val_2 = rts
+
+
 ############# TCP port settings #############
 
 # TCP server address to bind
diff --git a/src/cfg.c b/src/cfg.c
index deb522c..a7a8a0f 100644
--- a/src/cfg.c
+++ b/src/cfg.c
@@ -40,7 +40,9 @@
 #define CFG_MAX_LINE_LENGTH 200
 
 #define CFG_NAME_MATCH(n) strcmp(n, name) == 0
+#define CFG_NAME_BEGINS(n) strncmp(n, name, strlen(n)) == 0
 #define CFG_VALUE_MATCH(n) strcasecmp(n, value) == 0
+#define CFG_VALUE_BEGINS(n) strncasecmp(n, value, strlen(n)) == 0
 #define CFG_VALUE_BOOL() (strcasecmp("y", value) == 0 || strcasecmp("yes", value) == 0)
 
 /* Global configuration storage variable */
@@ -70,6 +72,13 @@ cfg_init(void)
 #ifdef TRXCTL
   cfg.trxcntl = TRX_ADDC;
   *cfg.trxcntl_file = '\0';
+  cfg.trx_ioctl_req = -1;
+  cfg.trx_ioctl_arg_type = TRX_IOCTL_ARG_LONG;
+  cfg.trx_ioctl_arg_long = 0;
+  cfg.trx_ioctl_arg_struct = NULL;
+  cfg.trx_ioctl_num_values = 0;
+  cfg.trx_ioctl_rts_value_num = 0;
+  cfg.trx_ioctl_rts_value_invert = FALSE;
 #endif
   strncpy(cfg.serveraddr, DEFAULT_SERVERADDR, INTBUFSIZE);
   cfg.serverport = DEFAULT_SERVERPORT;
@@ -212,6 +221,10 @@ cfg_handle_param(char *name, char *value)
     {
       cfg.trxcntl = TRX_SYSFS_1;
     }
+    else if (CFG_VALUE_MATCH("ioctl"))
+    {
+      cfg.trxcntl = TRX_IOCTL;
+    }
     else
     {
       /* Unknown TRX control mode */
@@ -222,12 +235,146 @@ cfg_handle_param(char *name, char *value)
   else if (CFG_NAME_MATCH("trx_sysfile"))
   {
     strncpy(cfg.trxcntl_file, value, INTBUFSIZE);
+  }
+  else if (CFG_NAME_MATCH("trx_ioctl_req"))
+  {
+    char *end;
+    cfg.trx_ioctl_req = strtoul(value, &end, 0);
+    if (value == end || '\0' != *end)
+    {
+      CFG_ERR("invalid IOCTL request number: %s", value);
+      return 0;
+    }
+  }
+  else if (CFG_NAME_MATCH("trx_ioctl_arg_type"))
+  {
+    if (CFG_VALUE_MATCH("long"))
+    {
+      cfg.trx_ioctl_arg_type = TRX_IOCTL_ARG_LONG;
+    }
+    else if (CFG_VALUE_MATCH("struct"))
+    {
+      cfg.trx_ioctl_arg_type = TRX_IOCTL_ARG_STRUCT;
+    }
+    else
+    {
+      /* Unknown IOCTL argument type */
+      CFG_ERR("unknown IOCTL argument type: %s", value);
+      return 0;
+    }
+  }
+  else if (CFG_NAME_MATCH("trx_ioctl_val"))
+  {
+    if (cfg.trx_ioctl_arg_type == TRX_IOCTL_ARG_STRUCT)
+    {
+      CFG_ERR("cannot use \"%s\" with \"struct\" argument type", name);
+      return 0;
+    }
+
+    if (CFG_VALUE_BEGINS("rts"))
+    {
+      cfg.trx_ioctl_rts_value_num = 1;
+      if (value[3] == '\0')
+      {
+        cfg.trx_ioctl_rts_value_invert = FALSE;
+      }
+      else if (strcasecmp("_inv", value + 3) == 0)
+      {
+        cfg.trx_ioctl_rts_value_invert = TRUE;
+      }
+      else
+      {
+        CFG_ERR("invalid IOCTL value: %s", value);
+        return 0;
+      }
+    }
+    else
+    {
+        char *end;
+        cfg.trx_ioctl_arg_long = strtoul(value, &end, 0);
+        if (value == end || '\0' != *end)
+        {
+          CFG_ERR("invalid IOCTL argument: %s", value);
+          return 0;
+        }
+    }
+  }
+  else if (CFG_NAME_BEGINS("trx_ioctl_val_"))
+  {
+    if (cfg.trx_ioctl_arg_type != TRX_IOCTL_ARG_STRUCT)
+    {
+      CFG_ERR("\"%s\" only valid with \"struct\" argument type", name);
+      return 0;
+    }
+
+    char *end;
+    int ioctl_val_num = strtoul(name + 14, &end, 10);
+    if ((name + 14) == end || '\0' != *end)
+    {
+      CFG_ERR("invalid IOCTL value number: %s", name + 14);
+      return 0;
+    }
+
+    if (cfg.trx_ioctl_num_values < ioctl_val_num)
+    {
+      // "reallocarray" not available in uClibc on embedded system, so had to use realloc instead
+      // using overflow-safe implementation like libc - could be considered overkill, but
+      // I really prefer to be cautious when it comes to memory allocation!
+
+      //cfg.trx_ioctl_arg_struct = reallocarray(cfg.trx_ioctl_arg_struct, ioctl_val_num, sizeof(unsigned long));
+      size_t newsize;
+      if(!__builtin_mul_overflow(ioctl_val_num, sizeof(unsigned long), &newsize))
+      {
+        cfg.trx_ioctl_arg_struct = realloc(cfg.trx_ioctl_arg_struct, newsize);
+      }
+      else
+      {
+        free(cfg.trx_ioctl_arg_struct);
+        cfg.trx_ioctl_arg_struct = NULL;
+        errno = ENOMEM;
+      }
+      if (!cfg.trx_ioctl_arg_struct)
+      {
+        CFG_ERR("cannot allocate memory for cfg parameter %s, exiting", name);
+        exit(errno);
+      }
+
+      cfg.trx_ioctl_num_values = ioctl_val_num;
+    }
+
+    if (CFG_VALUE_BEGINS("rts"))
+    {
+      cfg.trx_ioctl_rts_value_num = ioctl_val_num;
+      if (value[3] == '\0')
+      {
+        cfg.trx_ioctl_rts_value_invert = FALSE;
+      }
+      else if (CFG_VALUE_MATCH("rts_inv") == 0)
+      {
+        cfg.trx_ioctl_rts_value_invert = TRUE;
+      }
+      else
+      {
+        CFG_ERR("invalid IOCTL value: %s", value);
+        return 0;
+      }
+    }
+    else
+    {
+        int ioctl_val = strtoul(value, &end, 0);
+        if (value == end || '\0' != *end)
+        {
+          CFG_ERR("invalid IOCTL value: %s", value);
+          return 0;
+        }
+        cfg.trx_ioctl_arg_struct[ioctl_val_num - 1] = ioctl_val;
+    }
 #endif
 #ifdef LOG
   }
   else if (CFG_NAME_MATCH("loglevel"))
   {
-    cfg.dbglvl = (char)strtol(optarg, NULL, 0);
+    cfg.dbglvl = (char)strtol(value, NULL, 0);
 #endif
   }
   else {
diff --git a/src/cfg.h b/src/cfg.h
index f4b7fbd..85c453e 100644
--- a/src/cfg.h
+++ b/src/cfg.h
@@ -63,6 +63,18 @@ typedef struct
   int trxcntl;
   /* trx control sysfs file */
   char trxcntl_file[INTBUFSIZE + 1];
+  /* trx IOCTL request number */
+  unsigned long trx_ioctl_req;
+  /* trx IOCTL argument type */
+  int trx_ioctl_arg_type;
+  /* trx IOCTL argument */
+  unsigned long trx_ioctl_arg_long;
+  unsigned long *trx_ioctl_arg_struct;
+  int trx_ioctl_rts_value_num;
+  int trx_ioctl_rts_value_invert;
+  /* number of values in IOCTL argument (if struct type) */
+  int trx_ioctl_num_values;
+  /* 
 #endif
   /* TCP server address */
   char serveraddr[INTBUFSIZE + 1];
diff --git a/src/tty.c b/src/tty.c
index 92462c7..1e3d5bd 100644
--- a/src/tty.c
+++ b/src/tty.c
@@ -461,7 +461,51 @@ void sysfs_gpio_set(char *filename, char *value) {
 	write(fd, value, 1);
 	close(fd);
 
+#ifdef LOG
 	logw(9, "tty: sysfs_gpio_set(%s,%s)\n",filename,value);
+#endif
+
+}
+
+void sysfs_gpio_ioctl(char *filename, int set) {
+	int fd;
+
+#ifdef LOG
+	logw(9, "tty: sysfs_gpio_ioctl(%s,%d)\n",filename,set);
+#endif
+
+    if (cfg.trx_ioctl_rts_value_invert)
+      set = !set;
+
+    if (cfg.trx_ioctl_rts_value_num > 0)
+    {
+      if (cfg.trx_ioctl_arg_type == TRX_IOCTL_ARG_STRUCT)
+        cfg.trx_ioctl_arg_struct[cfg.trx_ioctl_rts_value_num - 1] = set;
+      else if (cfg.trx_ioctl_arg_type == TRX_IOCTL_ARG_LONG)
+        cfg.trx_ioctl_arg_long = set;
+    }
+
+	fd = open(filename, O_WRONLY);
+	if (cfg.trx_ioctl_arg_type == TRX_IOCTL_ARG_LONG)
+		ioctl(fd, cfg.trx_ioctl_req, cfg.trx_ioctl_arg_long);
+	else if (cfg.trx_ioctl_arg_type == TRX_IOCTL_ARG_STRUCT)
+		ioctl(fd, cfg.trx_ioctl_req, cfg.trx_ioctl_arg_struct);
+
+	close(fd);
+
+#ifdef LOG
+    logw(9, "tty: ioctl request = 0x%lx\n",cfg.trx_ioctl_req);
+
+    if (cfg.trx_ioctl_arg_type == TRX_IOCTL_ARG_LONG)
+      logw(9, "tty: ioctl arg = 0x%lx\n",cfg.trx_ioctl_arg_long);
+
+    if (cfg.trx_ioctl_arg_type == TRX_IOCTL_ARG_STRUCT)
+    {
+      logw(9, "tty: ioctl struct: %d values\n",cfg.trx_ioctl_num_values);
+      for(int i = 0; i < cfg.trx_ioctl_num_values; i++)
+        logw(9, "tty: ioctl struct value %d = 0x%lx\n",i,cfg.trx_ioctl_arg_struct[i]);
+    }
+#endif
 
 }
 
@@ -476,7 +520,10 @@ tty_set_rts(int fd)
 		sysfs_gpio_set(cfg.trxcntl_file,"1");
 	} else if ( TRX_SYSFS_0 == cfg.trxcntl) {
 		sysfs_gpio_set(cfg.trxcntl_file,"0");
+	} else if ( TRX_IOCTL == cfg.trxcntl) {
+		sysfs_gpio_ioctl(cfg.trxcntl_file,1);
 	}
+
 }
 
 /* Set RTS line to passive state */
@@ -490,7 +537,10 @@ tty_clr_rts(int fd)
 		sysfs_gpio_set(cfg.trxcntl_file,"0");
 	} else if ( TRX_SYSFS_0 == cfg.trxcntl) {
 		sysfs_gpio_set(cfg.trxcntl_file,"1");
+	} else if ( TRX_IOCTL == cfg.trxcntl) {
+		sysfs_gpio_ioctl(cfg.trxcntl_file,0);
 	}
+
 }
 #endif
 
diff --git a/src/tty.h b/src/tty.h
index fe7d82f..1edefe6 100644
--- a/src/tty.h
+++ b/src/tty.h
@@ -80,6 +80,13 @@
 #define TRX_RTS     1
 #define TRX_SYSFS_1 2
 #define TRX_SYSFS_0 3
+#define TRX_IOCTL   4
+
+/*
+ * TRX IOCTL argument types
+ */
+#define TRX_IOCTL_ARG_LONG   0
+#define TRX_IOCTL_ARG_STRUCT 1
 #endif
 
 /*