QIoT node-red-contrib-modbus Modbus-Flex-Getter "PortNotOpenError: Port Not Open"

Hi there !

I'm trying to use the QNAP QIoT Suite to read values on a Modbus probe. This Suite is using NodeRed. I'm using the node-red-contrib-modbus module.

The probe is connected to a RS485 Module witch is itself connected on a RaspberryPi with the 192.168.1.22 IP adress.

There is my configuration :
Inject > Function > Modbus-Flex-Getter > Modbus Response

Debug

Setup as following :

Inject :
Chain []

Function :
msg.payload = {
'fc': 3,
'unitid': 10,
'address': 164,
'quantity': 1};
return msg;

Modbus-Flex-Getter :
Modbus Client :

Nœud "a2c729b5.350318"
Nom test
Type modbus-client
clienttype "serial"
bufferCommands true
stateLogEnabled false
tcpHost "192.168.1.22"
tcpPort "502"
tcpType "DEFAULT"
serialPort "192.168.1.22/dev/ttyUSB0"
serialType "RTU"
serialBaudrate "9600"
serialDatabits "8"
serialStopbits "2"
serialParity "none"
serialConnectionDelay "100"
unit_id 10
commandDelay 1
clientTimeout 1000
reconnectOnTimeout false
reconnectTimeout 2000
parallelUnitIdsAllowed true

When I trigger the "Inject" node I get these messages :
14/01/2020 à 15:50:26node: 23caa4eb.b96e1c
msg : PortNotOpenError
"PortNotOpenError: Port Not Open"
14/01/2020 à 15:50:26node: 23caa4eb.b96e1cmsg : string[65]
"FSM Reset On State {"value":"failed","actions":,"changed":true}"
14/01/2020 à 15:50:26node: 23caa4eb.b96e1cmsg : string[65]
"FSM Reset On State {"value":"failed","actions":,"changed":true}"

NodeRed is completely new for me and I don't quite get what is the issue here ! Any help ?