diff --git a/src/modbus-private.h b/src/modbus-private.h
index 2c601c495..3e854f117 100644
--- a/src/modbus-private.h
+++ b/src/modbus-private.h
@@ -106,6 +106,7 @@ struct _modbus {
 void _modbus_init_common(modbus_t *ctx);
 void _error_print(modbus_t *ctx, const char *context);
 int _modbus_receive_msg(modbus_t *ctx, uint8_t *msg, msg_type_t msg_type);
+void _modbus_free_files(modbus_file_t *files, int nb_files);
 
 #ifndef HAVE_STRLCPY
 size_t strlcpy(char *dest, const char *src, size_t dest_size);
diff --git a/src/modbus.c b/src/modbus.c
index 4a30cc73b..163170223 100644
--- a/src/modbus.c
+++ b/src/modbus.c
@@ -1893,9 +1893,12 @@ modbus_mapping_t* modbus_mapping_new_start_address(
     unsigned int start_bits, unsigned int nb_bits,
     unsigned int start_input_bits, unsigned int nb_input_bits,
     unsigned int start_registers, unsigned int nb_registers,
-    unsigned int start_input_registers, unsigned int nb_input_registers)
+    unsigned int start_input_registers, unsigned int nb_input_registers,
+    unsigned int start_files, unsigned int nb_files,
+    unsigned int nb_records, unsigned int record_size)
 {
     modbus_mapping_t *mb_mapping;
+    unsigned int i, j;
 
     mb_mapping = (modbus_mapping_t *)malloc(sizeof(modbus_mapping_t));
     if (mb_mapping == NULL) {
@@ -1970,16 +1973,88 @@ modbus_mapping_t* modbus_mapping_new_start_address(
                nb_input_registers * sizeof(uint16_t));
     }
 
+    /* 5X */
+    mb_mapping->nb_files = nb_files;
+    mb_mapping->start_files = start_files;
+    if (nb_files == 0) {
+        mb_mapping->files = NULL;
+    } else {
+        mb_mapping->files = (modbus_file_t *) malloc(nb_files * sizeof(modbus_file_t));
+        if (mb_mapping->files == NULL) {
+            free(mb_mapping->tab_input_registers);
+            free(mb_mapping->tab_registers);
+            free(mb_mapping->tab_input_bits);
+            free(mb_mapping->tab_bits);
+            free(mb_mapping);
+            return NULL;
+        }
+        memset(mb_mapping->files, 0,
+               nb_files * sizeof(modbus_file_t));
+
+        for (i = 0; i < nb_files; i++) {
+            mb_mapping->files[i].nb_records = nb_records;
+            mb_mapping->files[i].record_size = record_size;
+            mb_mapping->files[i].records = (uint16_t **) malloc(nb_records * sizeof(uint16_t *));
+            if (mb_mapping->files[i].records == NULL) {
+                while (i) {
+                    free(mb_mapping->files[i--].records);
+                }
+                free(mb_mapping->files);
+                free(mb_mapping->tab_input_registers);
+                free(mb_mapping->tab_registers);
+                free(mb_mapping->tab_input_bits);
+                free(mb_mapping->tab_bits);
+                free(mb_mapping);
+                return NULL;
+            }
+            for (j = 0; j < nb_records; j++) {
+                mb_mapping->files[i].records[j] = (uint16_t *) malloc(record_size * sizeof(uint16_t));
+                if (mb_mapping->files[i].records[j] == NULL) {
+                    while (j) {
+                        free(mb_mapping->files[i].records[j--]);
+                    }
+                    while (i) {
+                        free(mb_mapping->files[i--].records);
+                    }
+                    free(mb_mapping->files);
+                    free(mb_mapping->tab_input_registers);
+                    free(mb_mapping->tab_registers);
+                    free(mb_mapping->tab_input_bits);
+                    free(mb_mapping->tab_bits);
+                    free(mb_mapping);
+                    return NULL;
+                }
+            }
+        }
+    }
+
     return mb_mapping;
 }
 
 modbus_mapping_t* modbus_mapping_new(int nb_bits, int nb_input_bits,
-                                     int nb_registers, int nb_input_registers)
+                                     int nb_registers, int nb_input_registers,
+                                     int nb_files, int nb_records, int record_size)
 {
     return modbus_mapping_new_start_address(
-        0, nb_bits, 0, nb_input_bits, 0, nb_registers, 0, nb_input_registers);
+        0, nb_bits, 0, nb_input_bits, 0, nb_registers, 0, nb_input_registers,
+        0, nb_files, nb_records, record_size);
 }
 
+void _modbus_free_files(modbus_file_t *files, int nb_files)
+{
+    int i, j;
+
+    if (files == NULL) {
+        return;
+    }
+
+    for (i = 0; i < nb_files; i++) {
+        for (j = 0; j < files[i].nb_records; j++) {
+            free(files[i].records[j]);
+        }
+        free(files[i].records);
+    }
+}
 /* Frees the 4 arrays */
 void modbus_mapping_free(modbus_mapping_t *mb_mapping)
 {
@@ -1991,6 +2066,8 @@ void modbus_mapping_free(modbus_mapping_t *mb_mapping)
     free(mb_mapping->tab_registers);
     free(mb_mapping->tab_input_bits);
     free(mb_mapping->tab_bits);
+    _modbus_free_files(mb_mapping->files, mb_mapping->nb_files);
+    free(mb_mapping->files);
     free(mb_mapping);
 }
 
diff --git a/src/modbus.h b/src/modbus.h
index 5983e68fd..fd63146d9 100644
--- a/src/modbus.h
+++ b/src/modbus.h
@@ -161,6 +161,12 @@ extern const unsigned int libmodbus_version_micro;
 
 typedef struct _modbus modbus_t;
 
+typedef struct _modbus_file_t {
+    int nb_records;
+    int record_size;
+    uint16_t **records;
+} modbus_file_t;
+
 typedef struct _modbus_mapping_t {
     int nb_bits;
     int start_bits;
@@ -170,10 +176,13 @@ typedef struct _modbus_mapping_t {
     int start_input_registers;
     int nb_registers;
     int start_registers;
+    int nb_files;
+    int start_files;
     uint8_t *tab_bits;
     uint8_t *tab_input_bits;
     uint16_t *tab_input_registers;
     uint16_t *tab_registers;
+    modbus_file_t *files;
 } modbus_mapping_t;
 
 typedef enum
@@ -230,10 +239,13 @@ MODBUS_API modbus_mapping_t* modbus_mapping_new_start_address(
     unsigned int start_bits, unsigned int nb_bits,
     unsigned int start_input_bits, unsigned int nb_input_bits,
     unsigned int start_registers, unsigned int nb_registers,
-    unsigned int start_input_registers, unsigned int nb_input_registers);
+    unsigned int start_input_registers, unsigned int nb_input_registers,
+    unsigned int start_files, unsigned int nb_files,
+    unsigned int nb_records, unsigned int record_size);
 
 MODBUS_API modbus_mapping_t* modbus_mapping_new(int nb_bits, int nb_input_bits,
-                                                int nb_registers, int nb_input_registers);
+                                                int nb_registers, int nb_input_registers,
+                                                int nb_files, int nb_records, int record_size);
 MODBUS_API void modbus_mapping_free(modbus_mapping_t *mb_mapping);
 
 MODBUS_API int modbus_send_raw_request(modbus_t *ctx, uint8_t *raw_req, int raw_req_length);
diff --git a/tests/bandwidth-server-many-up.c b/tests/bandwidth-server-many-up.c
index 0f00f3a2f..eb86db831 100644
--- a/tests/bandwidth-server-many-up.c
+++ b/tests/bandwidth-server-many-up.c
@@ -53,7 +53,8 @@ int main(void)
     ctx = modbus_new_tcp("127.0.0.1", 1502);
 
     mb_mapping = modbus_mapping_new(MODBUS_MAX_READ_BITS, 0,
-                                    MODBUS_MAX_READ_REGISTERS, 0);
+                                    MODBUS_MAX_READ_REGISTERS, 0,
+                                    0, 0, 0);
     if (mb_mapping == NULL) {
         fprintf(stderr, "Failed to allocate the mapping: %s\n",
                 modbus_strerror(errno));
diff --git a/tests/bandwidth-server-one.c b/tests/bandwidth-server-one.c
index 8971d0763..4519471f8 100644
--- a/tests/bandwidth-server-one.c
+++ b/tests/bandwidth-server-one.c
@@ -58,7 +58,8 @@ int main(int argc, char *argv[])
     }
 
     mb_mapping = modbus_mapping_new(MODBUS_MAX_READ_BITS, 0,
-                                    MODBUS_MAX_READ_REGISTERS, 0);
+                                    MODBUS_MAX_READ_REGISTERS, 0,
+                                    0, 0, 0);
     if (mb_mapping == NULL) {
         fprintf(stderr, "Failed to allocate the mapping: %s\n",
                 modbus_strerror(errno));
diff --git a/tests/random-test-server.c b/tests/random-test-server.c
index 03bd87056..e5b97a9ca 100644
--- a/tests/random-test-server.c
+++ b/tests/random-test-server.c
@@ -22,7 +22,7 @@ int main(void)
     ctx = modbus_new_tcp("127.0.0.1", 1502);
     /* modbus_set_debug(ctx, TRUE); */
 
-    mb_mapping = modbus_mapping_new(500, 500, 500, 500);
+    mb_mapping = modbus_mapping_new(500, 500, 500, 500, 0, 0, 0);
     if (mb_mapping == NULL) {
         fprintf(stderr, "Failed to allocate the mapping: %s\n",
                 modbus_strerror(errno));
diff --git a/tests/unit-test-server.c b/tests/unit-test-server.c
index 7002b10c6..834105d20 100644
--- a/tests/unit-test-server.c
+++ b/tests/unit-test-server.c
@@ -75,7 +75,8 @@ int main(int argc, char*argv[])
         UT_BITS_ADDRESS, UT_BITS_NB,
         UT_INPUT_BITS_ADDRESS, UT_INPUT_BITS_NB,
         UT_REGISTERS_ADDRESS, UT_REGISTERS_NB_MAX,
-        UT_INPUT_REGISTERS_ADDRESS, UT_INPUT_REGISTERS_NB);
+        UT_INPUT_REGISTERS_ADDRESS, UT_INPUT_REGISTERS_NB,
+        0, 0, 0, 0);
     if (mb_mapping == NULL) {
         fprintf(stderr, "Failed to allocate the mapping: %s\n",
                 modbus_strerror(errno));