diff --git a/Dockerfile b/Dockerfile
index 0b33e24..1d1757f 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -6,6 +6,8 @@ RUN apt-get update && apt-get -y install gunicorn sqlite3 python3-pip python3-re
 ENV PIP_BREAK_SYSTEM_PACKAGES 1
 RUN pip install flask-restx==1.3.0
 WORKDIR /root
+COPY find_ttyUSB.sh /root/
+COPY relay.py /root/
 COPY thermostat.py /root/
 ENV FLASK_APP thermostat.py
 ENTRYPOINT ["/usr/bin/gunicorn", "thermostat:gunicorn_app"]
diff --git a/README_relay.txt b/README_relay.txt
new file mode 100644
index 0000000..5fccd3a
--- /dev/null
+++ b/README_relay.txt
@@ -0,0 +1,76 @@
+*****************************************************************************
+Configuration port série: 1 start, 8 bit, 1 stop (vitesse 9600 bauds)
+*****************************************************************************
+La trame est composée de 5 caractères (minuscule ou majuscule) pouvant etre envoyés en ASCII ou en Hexadécimal
+
+****************
+Code ascii
+****************
+                          
+Start of frame: RLY
+N° channel: 0 à 8
+CMD: 0 ou 1
+
+Exemple de trame:
+
+RLY11 // commute le relais 1 en position travail
+RLY10 // commute le relais 1 en position repos
+RLY21 // commute le relais 2 en position travail
+...........................................................................
+RLY80 commute le relais 8 en position repos
+
+En cas de mauvaise commande la carte renvoi un retour chariot et le caractère ?
+
+****************
+Code hexa
+****************
+Start of frame:  0x52 0x4C 0x59 ou 0x72 0x6C 0x79
+N° channel: 0x31 à 0x38
+Cmd: 0x30 ou 0x31
+
+
+Exemple de trame:
+
+0x52 0x4C 0x59 0x31 0x31 // commute le relais 1 en position travail
+0x52 0x4C 0x59 0x31 0x30 // commute le relais 1 en position repos
+0x52 0x4C 0x59 0x32 0x31 // commute le relais 2 en position travail
+...........................................................................
+0x52 0x4C 0x59 0x38 0x30 commute le relais 8 en position repos
+
+Pour tout autre caractère ou chaines de caractères la carte renvoi le code suivant:
+0x0D 0x3F
+*******************************************************************************
+Modification du :04/09/2009
+*******************************************************************************
+
+Rajout du mode mémoire: la carte garde la dernière configuration en mémoire en cas de coupure d'alimentation.
+
+
+****************
+Code ascii 
+****************
+M0 // Mode mémore désactivé
+M1 // Mode mémoire activé
+
+****************
+Code hexa
+****************
+0x4D 0x30 // Mode mémore désactivé
+0x4D 0x31 // Mode mémoire activé
+*******************************************************************************
+
+Rajout d'une commande pour connaitre l'état des relais.
+
+
+****************
+Code ascii 
+****************
+?RLY // Renvoi l'état logique des 8 relais sous la forme >00000000   (le caractère le plus  à droite correspond au relais 8)
+
+****************
+Code hexa
+****************
+0X3F 0x52 0x4C 0x59 // Renvoi l'état logique des 8 relais sous la forme >00000000   (le caractère le plus  à droite correspond au relais 8)
+
+
+******************************************************************************
diff --git a/TODO b/TODO
new file mode 100644
index 0000000..8161b4c
--- /dev/null
+++ b/TODO
@@ -0,0 +1,3 @@
+- Upgrade relay.py to Python3
+- Retry after failure in relay.py
+- Store relays state in DB so we can have the info in /status API endpoint
diff --git a/find_ttyUSB.sh b/find_ttyUSB.sh
new file mode 100755
index 0000000..a224fe3
--- /dev/null
+++ b/find_ttyUSB.sh
@@ -0,0 +1,10 @@
+#!/bin/bash
+
+for sysdevpath in $(find /sys/bus/usb/devices/usb*/ -name dev); do
+    syspath="${sysdevpath%/dev}"
+    devname="$(udevadm info -q name -p $syspath)"
+    [[ "$devname" == "ttyUSB"* ]] || continue
+    eval "$(udevadm info -q property --export -p $syspath)"
+    [[ -z "$ID_SERIAL" ]] && exit
+    echo "/dev/$devname - $ID_SERIAL"
+done
diff --git a/relay.py b/relay.py
new file mode 100755
index 0000000..4b36627
--- /dev/null
+++ b/relay.py
@@ -0,0 +1,106 @@
+#!/usr/bin/env python3
+# Pilotage GCE USB 8 Relay Board
+import time
+import serial
+import argparse
+import sys
+import subprocess
+
+parser = argparse.ArgumentParser(description='Control relays.')
+parser.add_argument('relay_list', type=str,
+                    help='list of relays in ["1", ..., "8"] separated by comma, no spaces. "all" means all relays.')
+parser.add_argument('action', type=str, choices=['on', 'off', 'status'],
+                    help='Action on the list of relays.')
+
+args = parser.parse_args()
+
+if args.relay_list == 'all':
+  relays = [ 'RLY'+str(i) for i in range(1,9)]
+else:
+  relays = []
+  for relay in args.relay_list.split(','):
+    if relay in [ str(i) for i in range(1,9)]:
+      relays.append('RLY'+relay)
+    else:
+      print("ERROR: Relay '"+relay+"' does not exist.")
+      sys.exit(1)
+
+if args.action == 'on':
+  action = '1'
+elif args.action == 'off':
+  action = '0'
+else:
+  action = 'status'
+
+#print(relays)
+
+find_ttyUSB_output = subprocess.check_output(["./find_ttyUSB.sh"])
+device = None
+for line in find_ttyUSB_output.split("\n"):
+  if "FTDI_FT232R_USB_UART_A50285BI" in line:
+    device = line.split(" ")[0]
+    break
+
+if device is None:
+  print ("Relay board not found.")
+  sys.exit(1)
+
+
+def init_serial(pPort):         
+  global ser          
+  ser = serial.Serial()
+  ser.baudrate = 9600 
+  ser.port = pPort
+  ser.bytesize = 8
+  ser.parity = 'N'
+  ser.timeout = None
+  ser.xonxoff = False
+  ser.rtscts=False
+  ser.dsrdtr=False
+  ser.timeout = 1
+  ser.open()          
+
+  if ser.isOpen():
+    pass
+    #print('Connected to ' + ser.portstr) 
+  else:
+    print('Could not connect to ' + ser.portstr) 
+    sys.exit(1)
+
+init_serial(device)
+if action != 'status':
+  for relay in relays:
+    ser.write(relay.encode('ascii')+action+'\r\n')
+    bytes = ser.readline() 
+    #print ('Renvoie :\r\n' + bytes) 
+
+ser.write('?RLY\r\n')
+answer = ser.readline()
+status = ''
+for char in answer:
+  if char in ['0', '1']:
+    status+= char
+if len(status) != 8:
+  print(len(status))
+  print("ERROR: status cannot be parsed.")
+  print('status:\r\n' + status) 
+  sys.exit(1)
+elif action != 'status':
+  print ('status:\r\n' + status) 
+
+if action != 'status':
+  for i in range(1,9):
+    relay = status[i-1]
+    if relay not in ['0', '1']:
+      print("ERROR: unrecognized value '"+relay+"' for relay "+str(i))
+    elif relay in relays and relay != action:
+      print("ERROR: wrong status '"+relay+"' for relay "+str(i))
+else:
+  for i in [int(relay[3]) for relay in relays]:
+    relay = status[i-1]
+    if relay not in ['0', '1']:
+      print("ERROR: unrecognized value '"+relay+"' for relay "+str(i))
+    else:
+      print(relay, end='')
+
+ser.close()