diff --git a/sonoff/i18n.h b/sonoff/i18n.h
index e1d27221b..5e34007f3 100644
--- a/sonoff/i18n.h
+++ b/sonoff/i18n.h
@@ -60,6 +60,7 @@
 #define D_JSON_FLASHMODE "FlashMode"
 #define D_JSON_FLASHSIZE "FlashSize"
 #define D_JSON_FREEMEMORY "Free"
+#define D_JSON_FREQUENCY "Frequency"
 #define D_JSON_FROM "from"
 #define D_JSON_GAS "Gas"
 #define D_JSON_GATEWAY "Gateway"
diff --git a/sonoff/language/bg-BG.h b/sonoff/language/bg-BG.h
index 7f30252ec..b3aa97528 100644
--- a/sonoff/language/bg-BG.h
+++ b/sonoff/language/bg-BG.h
@@ -91,6 +91,7 @@
 #define D_FALSE "Невярно"
 #define D_FILE "Файл"
 #define D_FREE_MEMORY "Свободна памет"
+#define D_FREQUENCY "Frequency"
 #define D_GAS "Газ"
 #define D_GATEWAY "Шлюз"
 #define D_GROUP "Група"
@@ -453,10 +454,13 @@
 #define D_SENSOR_SBR_TX   "SerBr Tx"
 #define D_SENSOR_SR04_TRIG "SR04 Tri"
 #define D_SENSOR_SR04_ECHO "SR04 Ech"
+#define D_SENSOR_SDM120_TX "SDM120 Tx"
+#define D_SENSOR_SDM120_RX "SDM120 Rx"
 
 // Units
 #define D_UNIT_AMPERE "А"
 #define D_UNIT_CENTIMETER "см"
+#define D_UNIT_HERTZ "Hz"
 #define D_UNIT_HOUR "ч"
 #define D_UNIT_KILOOHM "кОм"
 #define D_UNIT_KILOWATTHOUR "кВт/ч"
diff --git a/sonoff/language/cs-CZ.h b/sonoff/language/cs-CZ.h
index a52f31901..6c07717c9 100644
--- a/sonoff/language/cs-CZ.h
+++ b/sonoff/language/cs-CZ.h
@@ -91,6 +91,7 @@
 #define D_FALSE "Nepravda"
 #define D_FILE "Soubor"
 #define D_FREE_MEMORY "Volná paměť"
+#define D_FREQUENCY "Frequency"
 #define D_GAS "Plyn"
 #define D_GATEWAY "Výchozí brána"
 #define D_GROUP "Skupina"
@@ -453,10 +454,13 @@
 #define D_SENSOR_SBR_TX   "SerBr Tx"
 #define D_SENSOR_SR04_TRIG "SR04 Tri"
 #define D_SENSOR_SR04_ECHO "SR04 Ech"
+#define D_SENSOR_SDM120_TX "SDM120 Tx"
+#define D_SENSOR_SDM120_RX "SDM120 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
 #define D_UNIT_CENTIMETER "cm"
+#define D_UNIT_HERTZ "Hz"
 #define D_UNIT_HOUR "hod"
 #define D_UNIT_KILOOHM "kOhm"
 #define D_UNIT_KILOWATTHOUR "kWh"
diff --git a/sonoff/language/de-DE.h b/sonoff/language/de-DE.h
index b2ade5e2b..d2808dd9c 100644
--- a/sonoff/language/de-DE.h
+++ b/sonoff/language/de-DE.h
@@ -91,6 +91,7 @@
 #define D_FALSE "falsch"
 #define D_FILE "Datei"
 #define D_FREE_MEMORY "Freier Arbeitsspeicher"
+#define D_FREQUENCY "Frequency"
 #define D_GAS "Gas"
 #define D_GATEWAY "Gateway"
 #define D_GROUP "Gruppe"
@@ -453,10 +454,13 @@
 #define D_SENSOR_SBR_TX   "SerBr Tx"
 #define D_SENSOR_SR04_TRIG "SR04 Tri"
 #define D_SENSOR_SR04_ECHO "SR04 Ech"
+#define D_SENSOR_SDM120_TX "SDM120 Tx"
+#define D_SENSOR_SDM120_RX "SDM120 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
 #define D_UNIT_CENTIMETER "cm"
+#define D_UNIT_HERTZ "Hz"
 #define D_UNIT_HOUR "h"
 #define D_UNIT_KILOOHM "kOhm"
 #define D_UNIT_KILOWATTHOUR "kWh"
diff --git a/sonoff/language/el-GR.h b/sonoff/language/el-GR.h
index e4280b092..595281610 100644
--- a/sonoff/language/el-GR.h
+++ b/sonoff/language/el-GR.h
@@ -91,6 +91,7 @@
 #define D_FALSE "Λάθος"
 #define D_FILE "Αρχείο"
 #define D_FREE_MEMORY "Ελεύθερη Μνήμη"
+#define D_FREQUENCY "Frequency"
 #define D_GAS "Γκάζι"
 #define D_GATEWAY "Πύλη"
 #define D_GROUP "Ομάδα"
@@ -453,10 +454,13 @@
 #define D_SENSOR_SBR_TX   "SerBr Tx"
 #define D_SENSOR_SR04_TRIG "SR04 Tri"
 #define D_SENSOR_SR04_ECHO "SR04 Ech"
+#define D_SENSOR_SDM120_TX "SDM120 Tx"
+#define D_SENSOR_SDM120_RX "SDM120 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
 #define D_UNIT_CENTIMETER "cm"
+#define D_UNIT_HERTZ "Hz"
 #define D_UNIT_HOUR "Hr"
 #define D_UNIT_KILOOHM "kOhm"
 #define D_UNIT_KILOWATTHOUR "kWh"
diff --git a/sonoff/language/en-GB.h b/sonoff/language/en-GB.h
index ade787b9e..32ca90460 100644
--- a/sonoff/language/en-GB.h
+++ b/sonoff/language/en-GB.h
@@ -91,6 +91,7 @@
 #define D_FALSE "False"
 #define D_FILE "File"
 #define D_FREE_MEMORY "Free Memory"
+#define D_FREQUENCY "Frequency"
 #define D_GAS "Gas"
 #define D_GATEWAY "Gateway"
 #define D_GROUP "Group"
@@ -453,6 +454,8 @@
 #define D_SENSOR_SBR_TX   "SerBr Tx"
 #define D_SENSOR_SR04_TRIG "SR04 Tri"
 #define D_SENSOR_SR04_ECHO "SR04 Ech"
+#define D_SENSOR_SDM120_TX "SDM120 Tx"
+#define D_SENSOR_SDM120_RX "SDM120 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
@@ -476,6 +479,7 @@
 #define D_UNIT_VOLT "V"
 #define D_UNIT_WATT "W"
 #define D_UNIT_WATTHOUR "Wh"
+#define D_UNIT_HERTZ "Hz"
 
 // Log message prefix
 #define D_LOG_APPLICATION "APP: "  // Application
diff --git a/sonoff/language/es-AR.h b/sonoff/language/es-AR.h
index ded21e8e7..200af4e1a 100644
--- a/sonoff/language/es-AR.h
+++ b/sonoff/language/es-AR.h
@@ -91,6 +91,7 @@
 #define D_FALSE "Falso"
 #define D_FILE "Archivo"
 #define D_FREE_MEMORY "Memoria Libre"
+#define D_FREQUENCY "Frequency"
 #define D_GAS "Gas"
 #define D_GATEWAY "Gateway"
 #define D_GROUP "Grupo"
@@ -453,10 +454,13 @@
 #define D_SENSOR_SBR_TX   "SerBr Tx"
 #define D_SENSOR_SR04_TRIG "SR04 Tri"
 #define D_SENSOR_SR04_ECHO "SR04 Ech"
+#define D_SENSOR_SDM120_TX "SDM120 Tx"
+#define D_SENSOR_SDM120_RX "SDM120 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
 #define D_UNIT_CENTIMETER "cm"
+#define D_UNIT_HERTZ "Hz"
 #define D_UNIT_HOUR "Hr"
 #define D_UNIT_KILOOHM "kOhm"
 #define D_UNIT_KILOWATTHOUR "kWh"
diff --git a/sonoff/language/fr-FR.h b/sonoff/language/fr-FR.h
index a9211dab1..b13e22418 100644
--- a/sonoff/language/fr-FR.h
+++ b/sonoff/language/fr-FR.h
@@ -91,6 +91,7 @@
 #define D_FALSE "Faux"
 #define D_FILE "Fichier"
 #define D_FREE_MEMORY "Mémoire libre"
+#define D_FREQUENCY "Frequency"
 #define D_GAS "Gaz"
 #define D_GATEWAY "Passerelle"
 #define D_GROUP "Groupe"
@@ -453,10 +454,13 @@
 #define D_SENSOR_SBR_TX   "SerBr Tx"
 #define D_SENSOR_SR04_TRIG "SR04 Tri"
 #define D_SENSOR_SR04_ECHO "SR04 Ech"
+#define D_SENSOR_SDM120_TX "SDM120 Tx"
+#define D_SENSOR_SDM120_RX "SDM120 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
 #define D_UNIT_CENTIMETER "cm"
+#define D_UNIT_HERTZ "Hz"
 #define D_UNIT_HOUR "h"
 #define D_UNIT_KILOOHM "kΩ"
 #define D_UNIT_KILOWATTHOUR "kWh"
diff --git a/sonoff/language/hu-HU.h b/sonoff/language/hu-HU.h
index 51d9e146f..0a5c9a79c 100644
--- a/sonoff/language/hu-HU.h
+++ b/sonoff/language/hu-HU.h
@@ -91,6 +91,7 @@
 #define D_FALSE "Hamis"
 #define D_FILE "File"
 #define D_FREE_MEMORY "Szabad Memória"
+#define D_FREQUENCY "Frequency"
 #define D_GAS "Gáz"
 #define D_GATEWAY "Gateway"
 #define D_GROUP "Csoport"
@@ -453,10 +454,13 @@
 #define D_SENSOR_SBR_TX   "SerBr Tx"
 #define D_SENSOR_SR04_TRIG "SR04 Tri"
 #define D_SENSOR_SR04_ECHO "SR04 Ech"
+#define D_SENSOR_SDM120_TX "SDM120 Tx"
+#define D_SENSOR_SDM120_RX "SDM120 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
 #define D_UNIT_CENTIMETER "cm"
+#define D_UNIT_HERTZ "Hz"
 #define D_UNIT_HOUR "ó"
 #define D_UNIT_KILOOHM "kOhm"
 #define D_UNIT_KILOWATTHOUR "kWh"
diff --git a/sonoff/language/it-IT.h b/sonoff/language/it-IT.h
index e114c8176..85f91a0a2 100644
--- a/sonoff/language/it-IT.h
+++ b/sonoff/language/it-IT.h
@@ -91,6 +91,7 @@
 #define D_FALSE "Falso"
 #define D_FILE "File"
 #define D_FREE_MEMORY "Memoria Libera"
+#define D_FREQUENCY "Frequenza"
 #define D_GAS "Gas"
 #define D_GATEWAY "Gateway"
 #define D_GROUP "Gruppo"
@@ -453,10 +454,13 @@
 #define D_SENSOR_SBR_TX   "SerBr Tx"
 #define D_SENSOR_SR04_TRIG "SR04 Tri"
 #define D_SENSOR_SR04_ECHO "SR04 Ech"
+#define D_SENSOR_SDM120_TX "SDM120 Tx"
+#define D_SENSOR_SDM120_RX "SDM120 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
 #define D_UNIT_CENTIMETER "cm"
+#define D_UNIT_HERTZ "Hz"
 #define D_UNIT_HOUR "Hr"
 #define D_UNIT_KILOOHM "kOhm"
 #define D_UNIT_KILOWATTHOUR "kWh"
diff --git a/sonoff/language/nl-NL.h b/sonoff/language/nl-NL.h
index 5d3bcb959..ba17c5db4 100644
--- a/sonoff/language/nl-NL.h
+++ b/sonoff/language/nl-NL.h
@@ -91,6 +91,7 @@
 #define D_FALSE "Onwaar"
 #define D_FILE "Bestand"
 #define D_FREE_MEMORY "Vrij geheugen"
+#define D_FREQUENCY "Frequency"
 #define D_GAS "Gas"
 #define D_GATEWAY "Gateway"
 #define D_GROUP "Groep"
@@ -453,10 +454,13 @@
 #define D_SENSOR_SBR_TX   "SerBr Tx"
 #define D_SENSOR_SR04_TRIG "SR04 Tri"
 #define D_SENSOR_SR04_ECHO "SR04 Ech"
+#define D_SENSOR_SDM120_TX "SDM120 Tx"
+#define D_SENSOR_SDM120_RX "SDM120 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
 #define D_UNIT_CENTIMETER "cm"
+#define D_UNIT_HERTZ "Hz"
 #define D_UNIT_HOUR "h"
 #define D_UNIT_KILOOHM "kOhm"
 #define D_UNIT_KILOWATTHOUR "kWh"
diff --git a/sonoff/language/pl-PL.h b/sonoff/language/pl-PL.h
index 19a27ebeb..e1b1a5878 100644
--- a/sonoff/language/pl-PL.h
+++ b/sonoff/language/pl-PL.h
@@ -91,6 +91,7 @@
 #define D_FALSE "Fałsz"
 #define D_FILE "Plik"
 #define D_FREE_MEMORY "Wolna pamięć"
+#define D_FREQUENCY "Frequency"
 #define D_GAS "Gas"
 #define D_GATEWAY "Brama"
 #define D_GROUP "Grupa"
@@ -453,10 +454,13 @@
 #define D_SENSOR_SBR_TX   "SerBr Tx"
 #define D_SENSOR_SR04_TRIG "SR04 Tri"
 #define D_SENSOR_SR04_ECHO "SR04 Ech"
+#define D_SENSOR_SDM120_TX "SDM120 Tx"
+#define D_SENSOR_SDM120_RX "SDM120 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
 #define D_UNIT_CENTIMETER "cm"
+#define D_UNIT_HERTZ "Hz"
 #define D_UNIT_HOUR "Godz"
 #define D_UNIT_KILOOHM "kOhm"
 #define D_UNIT_KILOWATTHOUR "kWh"
diff --git a/sonoff/language/pt-BR.h b/sonoff/language/pt-BR.h
index a279782eb..83f53a165 100644
--- a/sonoff/language/pt-BR.h
+++ b/sonoff/language/pt-BR.h
@@ -91,6 +91,7 @@
 #define D_FALSE "Falso"
 #define D_FILE "Arquivo"
 #define D_FREE_MEMORY "Memória Livre"
+#define D_FREQUENCY "Frequency"
 #define D_GAS "Gás"
 #define D_GATEWAY "Gateway"
 #define D_GROUP "Grupo"
@@ -453,10 +454,13 @@
 #define D_SENSOR_SBR_TX   "SerBr Tx"
 #define D_SENSOR_SR04_TRIG "SR04 Tri"
 #define D_SENSOR_SR04_ECHO "SR04 Ech"
+#define D_SENSOR_SDM120_TX "SDM120 Tx"
+#define D_SENSOR_SDM120_RX "SDM120 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
 #define D_UNIT_CENTIMETER "cm"
+#define D_UNIT_HERTZ "Hz"
 #define D_UNIT_HOUR "H"
 #define D_UNIT_KILOOHM "kOhm"
 #define D_UNIT_KILOWATTHOUR "kWh"
diff --git a/sonoff/language/pt-PT.h b/sonoff/language/pt-PT.h
index 149aeec31..9765830bd 100644
--- a/sonoff/language/pt-PT.h
+++ b/sonoff/language/pt-PT.h
@@ -91,6 +91,7 @@
 #define D_FALSE "Falso"
 #define D_FILE "Ficheiro"
 #define D_FREE_MEMORY "Memoria Livre"
+#define D_FREQUENCY "Frequency"
 #define D_GAS "Gás"
 #define D_GATEWAY "Gateway"
 #define D_GROUP "Grupo"
@@ -453,10 +454,13 @@
 #define D_SENSOR_SBR_TX   "SerBr Tx"
 #define D_SENSOR_SR04_TRIG "SR04 Tri"
 #define D_SENSOR_SR04_ECHO "SR04 Ech"
+#define D_SENSOR_SDM120_TX "SDM120 Tx"
+#define D_SENSOR_SDM120_RX "SDM120 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
 #define D_UNIT_CENTIMETER "cm"
+#define D_UNIT_HERTZ "Hz"
 #define D_UNIT_HOUR "Hr"
 #define D_UNIT_KILOOHM "kOhm"
 #define D_UNIT_KILOWATTHOUR "kWh"
diff --git a/sonoff/language/ru-RU.h b/sonoff/language/ru-RU.h
index 96ad631ab..c19eccbf1 100644
--- a/sonoff/language/ru-RU.h
+++ b/sonoff/language/ru-RU.h
@@ -91,6 +91,7 @@
 #define D_FALSE "Ложно"
 #define D_FILE "Файл"
 #define D_FREE_MEMORY "Свободная память"
+#define D_FREQUENCY "Frequency"
 #define D_GAS "Газ"
 #define D_GATEWAY "Шлюз"
 #define D_GROUP "Группа"
@@ -453,10 +454,13 @@
 #define D_SENSOR_SBR_TX   "SerBr Tx"
 #define D_SENSOR_SR04_TRIG "SR04 Tri"
 #define D_SENSOR_SR04_ECHO "SR04 Ech"
+#define D_SENSOR_SDM120_TX "SDM120 Tx"
+#define D_SENSOR_SDM120_RX "SDM120 Rx"
 
 // Units
 #define D_UNIT_AMPERE "А"
 #define D_UNIT_CENTIMETER "cm"
+#define D_UNIT_HERTZ "Hz"
 #define D_UNIT_HOUR "Ч"
 #define D_UNIT_KILOOHM "кОм"
 #define D_UNIT_KILOWATTHOUR "кВт"
diff --git a/sonoff/language/zh-CN.h b/sonoff/language/zh-CN.h
index b90ab7b1d..c10cbdc16 100644
--- a/sonoff/language/zh-CN.h
+++ b/sonoff/language/zh-CN.h
@@ -91,6 +91,7 @@
 #define D_FALSE "False"
 #define D_FILE "文件:"
 #define D_FREE_MEMORY "空闲内存"
+#define D_FREQUENCY "Frequency"
 #define D_GAS "气体"
 #define D_GATEWAY "网关"
 #define D_GROUP "组:"
@@ -453,10 +454,13 @@
 #define D_SENSOR_SBR_TX   "SerBr Tx"
 #define D_SENSOR_SR04_TRIG "SR04 Tri"
 #define D_SENSOR_SR04_ECHO "SR04 Ech"
+#define D_SENSOR_SDM120_TX "SDM120 Tx"
+#define D_SENSOR_SDM120_RX "SDM120 Rx"
 
 // Units
 #define D_UNIT_AMPERE "安"
 #define D_UNIT_CENTIMETER "cm"
+#define D_UNIT_HERTZ "Hz"
 #define D_UNIT_HOUR "时"
 #define D_UNIT_KILOOHM "千欧"
 #define D_UNIT_KILOWATTHOUR "千瓦时"
diff --git a/sonoff/language/zh-TW.h b/sonoff/language/zh-TW.h
index b13f0ba04..e2c5b9193 100644
--- a/sonoff/language/zh-TW.h
+++ b/sonoff/language/zh-TW.h
@@ -91,6 +91,7 @@
 #define D_FALSE "False"
 #define D_FILE "文件:"
 #define D_FREE_MEMORY "可用記憶體"
+#define D_FREQUENCY "Frequency"
 #define D_GAS "氣體"
 #define D_GATEWAY "網關"
 #define D_GROUP "組:"
@@ -453,10 +454,13 @@
 #define D_SENSOR_SBR_TX   "SerBr Tx"
 #define D_SENSOR_SR04_TRIG "SR04 Tri"
 #define D_SENSOR_SR04_ECHO "SR04 Ech"
+#define D_SENSOR_SDM120_TX "SDM120 Tx"
+#define D_SENSOR_SDM120_RX "SDM120 Rx"
 
 // Units
 #define D_UNIT_AMPERE "安"
 #define D_UNIT_CENTIMETER "cm"
+#define D_UNIT_HERTZ "Hz"
 #define D_UNIT_HOUR "時"
 #define D_UNIT_KILOOHM "千歐"
 #define D_UNIT_KILOWATTHOUR "千瓦時"
diff --git a/sonoff/sonoff_template.h b/sonoff/sonoff_template.h
index dc0746ec7..7eb4ce225 100644
--- a/sonoff/sonoff_template.h
+++ b/sonoff/sonoff_template.h
@@ -93,6 +93,8 @@ enum UserSelectablePins {
   GPIO_SBR_RX,         // Serial Bridge Serial interface
   GPIO_SR04_TRIG,      // SR04 Trigger pin
   GPIO_SR04_ECHO,      // SR04 Echo pin
+  GPIO_SDM120_TX,      // SDM120 Serial interface
+  GPIO_SDM120_RX,      // SDM120 Serial interface
   GPIO_SENSOR_END };
 
 // Programmer selectable GPIO functionality offset by user selectable GPIOs
@@ -136,7 +138,8 @@ const char kSensorNames[] PROGMEM =
   D_SENSOR_SPI_CS "|" D_SENSOR_SPI_DC "|" D_SENSOR_BACKLIGHT "|"
   D_SENSOR_PMS5003 "|" D_SENSOR_SDS0X1 "|"
   D_SENSOR_SBR_TX "|" D_SENSOR_SBR_RX "|"
-  D_SENSOR_SR04_TRIG "|" D_SENSOR_SR04_ECHO;
+  D_SENSOR_SR04_TRIG "|" D_SENSOR_SR04_ECHO "|"
+  D_SENSOR_SDM120_TX "|" D_SENSOR_SDM120_RX;
 
 /********************************************************************************************/
 
diff --git a/sonoff/user_config.h b/sonoff/user_config.h
index c8f4f4dbb..5c57d4478 100644
--- a/sonoff/user_config.h
+++ b/sonoff/user_config.h
@@ -280,6 +280,7 @@
 #define USE_NOVA_SDS                             // Add support for SDS011 and SDS021 particle concentration sensor (+0k7 code)
 #define USE_PZEM004T                             // Add support for PZEM004T Energy monitor (+2k code)
 #define USE_SERIAL_BRIDGE                        // Add support for software Serial Bridge (+0k8 code)
+#define USE_SDM120                               // Add support for Eastron SDM120-Modbus energy meter (+1k2 code)
 
 // -- Low level interface devices -----------------
 #define USE_IR_REMOTE                            // Send IR remote commands using library IRremoteESP8266 and ArduinoJson (+4k code, 0k3 mem, 48 iram)
diff --git a/sonoff/xsns_23_sdm120.ino b/sonoff/xsns_23_sdm120.ino
new file mode 100644
index 000000000..108d53075
--- /dev/null
+++ b/sonoff/xsns_23_sdm120.ino
@@ -0,0 +1,282 @@
+/*
+  xsns_23_sdm120.ino - Eastron SDM120-Modbus energy meter support for Sonoff-Tasmota
+
+  Copyright (C) 2018  Gennaro Tortone
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifdef USE_SDM120
+
+/*********************************************************************************************\
+ * Eastron SDM120-Modbus energy meter
+ *
+ * Based on: https://github.com/reaper7/SDM_Energy_Meter
+\*********************************************************************************************/
+
+#include <TasmotaSerial.h>
+
+TasmotaSerial *SDM120Serial;
+
+uint8_t sdm120_type = 1;
+uint8_t sdm120_state = 0;
+
+float sdm120_voltage = 0;
+float sdm120_current = 0;
+float sdm120_power = 0;
+float sdm120_power_factor = 0;
+float sdm120_frequency = 0;
+float sdm120_energy_total = 0;
+
+bool SDM_ModbusReceiveReady()
+{
+  return (SDM120Serial->available() > 1);
+}
+
+void SDM_ModbusSend(uint8_t function_code, uint16_t start_address, uint16_t register_count)
+{
+  uint8_t frame[8];
+
+  frame[0] = 0x01;          // default SDM120 Modbus address
+  frame[1] = function_code;
+  frame[2] = (uint8_t)(start_address >> 8);
+  frame[3] = (uint8_t)(start_address);
+  frame[4] = (uint8_t)(register_count >> 8);
+  frame[5] = (uint8_t)(register_count);
+
+  uint16_t crc = SDM_calculateCRC(frame, 6);  // calculate out crc only from first 6 bytes
+  frame[6] = lowByte(crc);
+  frame[7] = highByte(crc);
+
+  while (SDM120Serial->available() > 0)  {  // read serial if any old data is available
+    SDM120Serial->read();
+  }
+
+  SDM120Serial->flush();
+  SDM120Serial->write(frame, sizeof(frame));
+}
+
+uint8_t SDM_ModbusReceive(float *value)
+{
+  uint8_t buffer[9];
+
+  *value = NAN;
+  uint8_t len = 0;
+  while (SDM120Serial->available() > 0) {
+    buffer[len++] = (uint8_t)SDM120Serial->read();
+  }
+
+  if (len < 9)
+    return 3;   // SDM_ERR_NOT_ENOUGHT_BYTES
+
+  if (len == 9) {
+
+    if (buffer[0] == 0x01 && buffer[1] == 0x04 && buffer[2] == 4) {   // check node number, op code and reply bytes count
+
+      if((SDM_calculateCRC(buffer, 7)) == ((buffer[8] << 8) | buffer[7])) {  //calculate crc from first 7 bytes and compare with received crc (bytes 7 & 8)
+
+        ((uint8_t*)value)[3] = buffer[3];
+        ((uint8_t*)value)[2] = buffer[4];
+        ((uint8_t*)value)[1] = buffer[5];
+        ((uint8_t*)value)[0] = buffer[6];
+      
+      } else return 1; // SDM_ERR_CRC_ERROR
+    
+    } else return 2;  // SDM_ERR_WRONG_BYTES
+  }
+
+  return 0;   // SDM_ERR_NO_ERROR
+}
+
+uint16_t SDM_calculateCRC(uint8_t *frame, uint8_t num)
+{
+  uint16_t crc, flag;
+  crc = 0xFFFF;
+  for (uint8_t i = 0; i < num; i++) {
+    crc ^= frame[i];
+    for (uint8_t j = 8; j; j--) {
+      if ((crc & 0x0001) != 0) {        // If the LSB is set
+        crc >>= 1;                      // Shift right and XOR 0xA001
+        crc ^= 0xA001;
+      } else {                          // Else LSB is not set
+        crc >>= 1;                      // Just shift right
+      }
+    }
+  }
+  return crc;
+}
+
+/*********************************************************************************************/
+
+const uint16_t sdm_start_addresses[] {
+  0x0000,   // SDM120C_VOLTAGE  [V]
+  0x0006,   // SDM120C_CURRENT  [A]
+  0x000C,   // SDM120C_POWER    [W]
+  0x0012,   // SDM120C_ACTIVE_APPARENT_POWER  [VA]
+  0x0018,   // SDM120C_REACTIVE_APPARENT_POWER  [VAR]
+  0x001E,   // SDM120C_POWER_FACTOR
+  0x0046,   // SDM120C_FREQUENCY  [Hz]
+  0x0048,   // SDM120C_IMPORT_ACTIVE_ENERGY [Wh]
+  0x004A,   // SDM120C_EXPORT_ACTIVE_ENERGY [Wh]
+  0x0156    // SDM120C_TOTAL_ACTIVE_ENERGY  [Wh]
+};
+
+uint8_t sdm120_read_state = 0;
+uint8_t sdm120_send_retry = 0;
+
+void SDM12050ms()              // Every 50 mSec            
+{
+  sdm120_state++;
+  if (6 == sdm120_state) {     // Every 300 mSec
+    sdm120_state = 0;
+
+    float value = 0;
+    bool data_ready = SDM_ModbusReceiveReady();
+
+    if (data_ready) {
+      uint8_t error = SDM_ModbusReceive(&value);
+      if (error) {
+        snprintf_P(log_data, sizeof(log_data), PSTR(D_LOG_DEBUG "SDM120 response error %d"), error);
+        AddLog(LOG_LEVEL_DEBUG);
+      } else {
+        switch(sdm120_read_state) {
+          case 0:
+            sdm120_voltage = value;
+            break;
+
+          case 1:
+            sdm120_current = value;
+            break;
+
+          case 2:
+            sdm120_power = value;
+            break;
+
+          case 5:
+            sdm120_power_factor = value;
+            break;
+
+          case 6:
+            sdm120_frequency = value;
+            break;
+
+          case 9:
+            sdm120_energy_total = value;
+            break;
+        } // end switch
+
+        sdm120_read_state++;
+
+        if (sizeof(sdm_start_addresses)/2 == sdm120_read_state) {
+          sdm120_read_state = 0;
+        }
+      }
+    } // end data ready
+
+    if (0 == sdm120_send_retry || data_ready) {
+      sdm120_send_retry = 5;
+       SDM_ModbusSend(0x04, sdm_start_addresses[sdm120_read_state], 2);
+    } else {
+      sdm120_send_retry--;
+    }
+  } // end 300 ms
+}
+
+void SDM120Init()
+{
+  sdm120_type = 0;
+  if ((pin[GPIO_SDM120_RX] < 99) && (pin[GPIO_SDM120_TX] < 99)) {
+    SDM120Serial = new TasmotaSerial(pin[GPIO_SDM120_RX], pin[GPIO_SDM120_TX], 1);
+    if (SDM120Serial->begin(9600)) {
+      if (SDM120Serial->hardwareSerial()) { ClaimSerial(); }
+      sdm120_type = 1;
+    }
+  }
+}
+
+#ifdef USE_WEBSERVER
+const char HTTP_SNS_SDM120_DATA[] PROGMEM = "%s"
+  "{s}SDM120 " D_VOLTAGE "{m}%s " D_UNIT_VOLT "{e}"
+  "{s}SDM120 " D_CURRENT "{m}%s " D_UNIT_AMPERE "{e}"
+  "{s}SDM120 " D_POWERUSAGE "{m}%s " D_UNIT_WATT "{e}"
+  "{s}SDM120 " D_POWER_FACTOR "{m}%s{e}"
+  "{s}SDM120 " D_FREQUENCY "{m}%s " D_UNIT_HERTZ "{e}"
+  "{s}SDM120 " D_ENERGY_TOTAL "{m}%s " D_UNIT_KILOWATTHOUR "{e}";
+#endif  // USE_WEBSERVER
+
+void SDM120Show(boolean json)
+{
+  char voltage[10];
+  char current[10];
+  char power[10];
+  char power_factor[10];
+  char frequency[10];
+  char energy_total[10];
+
+  dtostrfd(sdm120_voltage, Settings.flag2.voltage_resolution, voltage);
+  dtostrfd(sdm120_current, Settings.flag2.current_resolution, current);
+  dtostrfd(sdm120_power, Settings.flag2.wattage_resolution, power);
+  dtostrfd(sdm120_power_factor, 2, power_factor);
+  dtostrfd(sdm120_frequency, 2, frequency);
+  dtostrfd(sdm120_energy_total, Settings.flag2.energy_resolution, energy_total);
+
+  if (json) {
+    snprintf_P(mqtt_data, sizeof(mqtt_data), PSTR("%s,\"" D_RSLT_ENERGY "\":{\"" D_JSON_TOTAL "\":%s,\"" D_JSON_POWERUSAGE "\":%s,\"" D_JSON_FREQUENCY "\":%s,\"" D_JSON_POWERFACTOR "\":%s,\"" D_JSON_VOLTAGE "\":%s,\"" D_JSON_CURRENT "\":%s}"),
+      mqtt_data, energy_total, power, frequency, power_factor, voltage, current);
+#ifdef USE_DOMOTICZ
+    if (0 == tele_period) { 
+      DomoticzSensor(DZ_VOLTAGE, voltage);
+      DomoticzSensor(DZ_CURRENT, current);
+      DomoticzSensorPowerEnergy((uint16_t)sdm120_power, energy_total); 
+    }
+#endif  // USE_DOMOTICZ
+#ifdef USE_WEBSERVER
+  } else {
+    snprintf_P(mqtt_data, sizeof(mqtt_data), HTTP_SNS_SDM120_DATA, mqtt_data, voltage, current, power, power_factor, frequency, energy_total);
+  }
+#endif  // USE_WEBSERVER
+}
+
+/*********************************************************************************************\
+ * Interface
+\*********************************************************************************************/
+
+#define XSNS_23
+
+boolean Xsns23(byte function)
+{
+  boolean result = false;
+
+  if (sdm120_type) {
+    switch (function) {
+      case FUNC_INIT:
+        SDM120Init();
+        break;
+      case FUNC_EVERY_50_MSECOND:
+        SDM12050ms();
+        break;
+      case FUNC_JSON_APPEND:
+        SDM120Show(1);
+        break;
+#ifdef USE_WEBSERVER
+      case FUNC_WEB_APPEND:
+        SDM120Show(0);
+        break;
+#endif  // USE_WEBSERVER
+    }
+  }
+  return result;
+}
+
+#endif   // USE_SDM120
\ No newline at end of file