Problem with modbus component

Goodmorning to all. Excuse Forgive me for my poor english.

I’m try to create an home automation system with five arduino connect to a RP2 that run home assistant.
The arduino’s are linker in a modbus network by 5 max 485 chip and the RP2 use a FDTI USB to rs485 converter.
The system work very well when i command switch by home assistant web interface but whe i see the log file, i find this tipe of error:

16-08-13 08:53:30 homeassistant.core: BusHandler:Exception doing job
Traceback (most recent call last):
File “/srv/hass/hass_venv/lib/python3.4/site-packages/homeassistant/core.py”, line 844, in job_handler
func(*args)
File “/srv/hass/hass_venv/lib/python3.4/site-packages/homeassistant/helpers/event.py”, line 179, in pattern_time_change_listener
action(now)
File “/srv/hass/hass_venv/lib/python3.4/site-packages/homeassistant/helpers/entity_component.py”, line 180, in _update_entity_states
entity.update_ha_state(True)
File “/srv/hass/hass_venv/lib/python3.4/site-packages/homeassistant/helpers/entity.py”, line 171, in update_ha_state
self.update()
File “/srv/hass/hass_venv/lib/python3.4/site-packages/homeassistant/components/switch/modbus.py”, line 116, in update
result = modbus.NETWORK.read_coils(address=self.register, count=1, unit=self.slave)
File “/home/hass/.homeassistant/deps/pymodbus/client/common.py”, line 43, in read_coils
return self.execute(request)
File “/home/hass/.homeassistant/deps/pymodbus/client/sync.py”, line 83, in execute
return self.transaction.execute(request)
File “/home/hass/.homeassistant/deps/pymodbus/transaction.py”, line 65, in execute
result = self.client._recv(1024)
File “/home/hass/.homeassistant/deps/pymodbus/client/sync.py”, line 354, in _recv
return self.socket.read(size)
File “/home/hass/.homeassistant/deps/serial/serialposix.py”, line 450, in read
ready, _, _ = select.select([self.fd, self.pipe_abort_read_r], [], [], timeout)
TypeError: argument must be an int, or have a fileno() method.

This reporting happens every 30 seconds for every switch of my configuration.

this is my configuration file:

modbus:
type: serial
method: rtu
port: /dev/ttyUSB0
baudrate: 38400
stopbits: 1
bytesize: 8
parity: N
timeout: 0.05

#creo gli slave

switch 1:
platform: modbus
slave: 1
coils:
100:
name: 1Arduino

switch 2:
platform: modbus
slave: 2
coils:
100:
name: 2Tamino

switch 3:
platform: modbus
slave: 3
coils:
100:
name: 3Mega

switch 4:
platform: modbus
slave: 4
coils:
100:
name: 4Nano1

switch 5:
platform: modbus
slave: 5
coils:
100:
name: 5Nano2.

Can someone help me to solve this problem.

Thanks, Miki.

Hi!

You using only one device?