from importlib import import_module
import attr
from ..factory import target_factory
from ..protocol import DigitalOutputProtocol
from ..util.proxy import proxymanager
from .common import Driver
from .exception import ExecutionError
[docs]
@target_factory.reg_driver
@attr.s(eq=False)
class ModbusCoilDriver(Driver, DigitalOutputProtocol):
bindings = {"coil": "ModbusTCPCoil", }
[docs]
def __attrs_post_init__(self):
super().__attrs_post_init__()
self._module = import_module('pyModbusTCP.client')
self._consts = import_module('pyModbusTCP.constants')
self.client = None
[docs]
def on_activate(self):
# we can only forward if the backend knows which port to use
host, port = proxymanager.get_host_and_port(self.coil, default_port=502)
self.client = self._module.ModbusClient(
host=host, port=int(port), auto_open=True, auto_close=True)
[docs]
def on_deactivate(self):
self.client = None
def _handle_error(self, action):
error_code = self.client.last_error
if error_code == self._consts.MB_EXCEPT_ERR:
exc = self.client.last_except
if exc not in [self._consts.EXP_ACKNOWLEDGE, self._consts.EXP_NONE]:
raise ExecutionError(
f'Could not {action} coil (code={error_code}/exception={exc})')
raise ExecutionError(f'Could not {action} coil (code={error_code})')
[docs]
@Driver.check_active
def set(self, status):
write_status = None
if self.coil.invert:
status = not status
if self.coil.write_multiple_coils:
write_status = self.client.write_multiple_coils(
self.coil.coil, [bool(status)]
)
else:
write_status = self.client.write_single_coil(self.coil.coil, bool(status))
if write_status is None:
self._handle_error("write")
[docs]
@Driver.check_active
def get(self):
status = self.client.read_coils(self.coil.coil)
if status is None:
self._handle_error("read")
status = status[0]
if self.coil.invert:
status = not status
return status