"""
Snap7 client used for connection to a siemens LOGO 7/8 server.
"""
import logging
import re
import struct
from ctypes import c_int, byref, c_uint16, c_int32
from ctypes import c_void_p
import snap7
from snap7 import types
from snap7.common import check_error, load_library, ipv4
from snap7.exceptions import Snap7Exception
from snap7.types import S7Object, WordLen
from snap7.types import param_types
logger = logging.getLogger(__name__)
[docs]class Logo:
"""
A snap7 Siemens Logo client:
There are two main comfort functions available :func:`Logo.read` and :func:`Logo.write`.
This functions realize a high level access to the VM addresses of the Siemens Logo just use the form:
Notes:
V10.3 for bit values
V10 for the complete byte
VW12 for a word (used for analog values)
For more information see examples for Siemens Logo 7 and 8
"""
[docs] def __init__(self):
"""Creates a new instance of :obj:`Logo`"""
self.pointer = None
self.library = load_library()
self.create()
def __del__(self):
self.destroy()
[docs] def create(self):
"""Create a SNAP7 client."""
logger.info("creating snap7 client")
self.library.Cli_Create.restype = c_void_p
self.pointer = S7Object(self.library.Cli_Create())
[docs] def destroy(self) -> int:
"""Destroy a client.
Returns:
Error code from snap7 library.
"""
logger.info("destroying snap7 client")
return self.library.Cli_Destroy(byref(self.pointer))
[docs] def disconnect(self) -> int:
"""Disconnect a client.
Returns:
Error code from snap7 library.
"""
logger.info("disconnecting snap7 client")
result = self.library.Cli_Disconnect(self.pointer)
check_error(result, context="client")
return result
[docs] def connect(self, ip_address: str, tsap_snap7: int, tsap_logo: int, tcpport: int = 102) -> int:
"""Connect to a Siemens LOGO server.
Notes:
Howto setup Logo communication configuration see: http://snap7.sourceforge.net/logo.html
Args:
ip_address: IP ip_address of server
tsap_snap7: TSAP SNAP7 Client (e.g. 10.00 = 0x1000)
tsap_logo: TSAP Logo Server (e.g. 20.00 = 0x2000)
Returns:
Error code from snap7 library.
"""
logger.info(f"connecting to {ip_address}:{tcpport} tsap_snap7 {tsap_snap7} tsap_logo {tsap_logo}")
# special handling for Siemens Logo
# 1st set connection params
# 2nd connect without any parameters
self.set_param(snap7.types.RemotePort, tcpport)
self.set_connection_params(ip_address, tsap_snap7, tsap_logo)
result = self.library.Cli_Connect(self.pointer)
check_error(result, context="client")
return result
[docs] def read(self, vm_address: str):
"""Reads from VM addresses of Siemens Logo. Examples: read("V40") / read("VW64") / read("V10.2")
Args:
vm_address: of Logo memory (e.g. V30.1, VW32, V24)
Returns:
integer
"""
area = types.Areas.DB
db_number = 1
size = 1
start = 0
wordlen: WordLen
logger.debug(f"read, vm_address:{vm_address}")
if re.match(r"V[0-9]{1,4}\.[0-7]", vm_address):
# bit value
logger.info(f"read, Bit address: {vm_address}")
address = vm_address[1:].split(".")
# transform string to int
address_byte = int(address[0])
address_bit = int(address[1])
start = (address_byte * 8) + address_bit
wordlen = WordLen.Bit
elif re.match("V[0-9]+", vm_address):
# byte value
logger.info(f"Byte address: {vm_address}")
start = int(vm_address[1:])
wordlen = WordLen.Byte
elif re.match("VW[0-9]+", vm_address):
# byte value
logger.info(f"Word address: {vm_address}")
start = int(vm_address[2:])
wordlen = WordLen.Word
elif re.match("VD[0-9]+", vm_address):
# byte value
logger.info(f"DWord address: {vm_address}")
start = int(vm_address[2:])
wordlen = WordLen.DWord
else:
logger.info("Unknown address format")
return 0
type_ = snap7.types.wordlen_to_ctypes[wordlen.value]
data = (type_ * size)()
logger.debug(f"start:{start}, wordlen:{wordlen.name}={wordlen.value}, data-length:{len(data)}")
result = self.library.Cli_ReadArea(self.pointer, area.value, db_number, start,
size, wordlen.value, byref(data))
check_error(result, context="client")
# transform result to int value
if wordlen == WordLen.Bit:
return data[0]
if wordlen == WordLen.Byte:
return struct.unpack_from(">B", data)[0]
if wordlen == WordLen.Word:
return struct.unpack_from(">h", data)[0]
if wordlen == WordLen.DWord:
return struct.unpack_from(">l", data)[0]
[docs] def write(self, vm_address: str, value: int) -> int:
"""Writes to VM addresses of Siemens Logo.
Args:
vm_address: write offset
value: integer
Examples:
>>> write("VW10", 200) or write("V10.3", 1)
"""
area = types.Areas.DB
db_number = 1
start = 0
amount = 1
wordlen: WordLen
data = bytearray(0)
logger.debug(f"write, vm_address:{vm_address}, value:{value}")
if re.match(r"^V[0-9]{1,4}\.[0-7]$", vm_address):
# bit value
logger.info(f"read, Bit address: {vm_address}")
address = vm_address[1:].split(".")
# transform string to int
address_byte = int(address[0])
address_bit = int(address[1])
start = (address_byte * 8) + address_bit
wordlen = WordLen.Bit
if value > 0:
data = bytearray([1])
else:
data = bytearray([0])
elif re.match("^V[0-9]+$", vm_address):
# byte value
logger.info(f"Byte address: {vm_address}")
start = int(vm_address[1:])
wordlen = WordLen.Byte
data = bytearray(struct.pack(">B", value))
elif re.match("^VW[0-9]+$", vm_address):
# byte value
logger.info(f"Word address: {vm_address}")
start = int(vm_address[2:])
wordlen = WordLen.Word
data = bytearray(struct.pack(">h", value))
elif re.match("^VD[0-9]+$", vm_address):
# byte value
logger.info(f"DWord address: {vm_address}")
start = int(vm_address[2:])
wordlen = WordLen.DWord
data = bytearray(struct.pack(">l", value))
else:
logger.info(f"write, Unknown address format: {vm_address}")
return 1
if wordlen == WordLen.Bit:
type_ = snap7.types.wordlen_to_ctypes[WordLen.Byte.value]
else:
type_ = snap7.types.wordlen_to_ctypes[wordlen.value]
cdata = (type_ * amount).from_buffer_copy(data)
logger.debug(f"write, vm_address:{vm_address} value:{value}")
result = self.library.Cli_WriteArea(self.pointer, area.value, db_number, start, amount, wordlen.value, byref(cdata))
check_error(result, context="client")
return result
[docs] def db_read(self, db_number: int, start: int, size: int) -> bytearray:
"""This is a lean function of Cli_ReadArea() to read PLC DB.
Args:
db_number: for Logo only DB=1
start: start address for Logo7 0..951 / Logo8 0..1469
size: in bytes
Returns:
Array of bytes
"""
logger.debug(f"db_read, db_number:{db_number}, start:{start}, size:{size}")
type_ = snap7.types.wordlen_to_ctypes[WordLen.Byte.value]
data = (type_ * size)()
result = (self.library.Cli_DBRead(
self.pointer, db_number, start, size,
byref(data)))
check_error(result, context="client")
return bytearray(data)
[docs] def db_write(self, db_number: int, start: int, data: bytearray) -> int:
"""Writes to a DB object.
Args:
db_number: for Logo only DB=1
start: start address for Logo7 0..951 / Logo8 0..1469
data: bytearray
Returns:
Error code from snap7 library.
"""
wordlen = WordLen.Byte
type_ = snap7.types.wordlen_to_ctypes[wordlen.value]
size = len(data)
cdata = (type_ * size).from_buffer_copy(data)
logger.debug(f"db_write db_number:{db_number} start:{start} size:{size} data:{data}")
result = self.library.Cli_DBWrite(self.pointer, db_number, start, size, byref(cdata))
check_error(result, context="client")
return result
[docs] def set_connection_params(self, ip_address: str, tsap_snap7: int, tsap_logo: int):
"""Sets internally (IP, LocalTSAP, RemoteTSAP) Coordinates.
Notes:
This function must be called just before Cli_Connect().
Args:
ip_address: IP ip_address of server
tsap_snap7: TSAP SNAP7 Client (e.g. 10.00 = 0x1000)
tsap_logo: TSAP Logo Server (e.g. 20.00 = 0x2000)
Raises:
:obj:`ValueError`: if the `ip_address` is not an IPV4.
:obj:`Snap7Exception`: if the snap7 error code is diferent from 0.
"""
if not re.match(ipv4, ip_address):
raise ValueError(f"{ip_address} is invalid ipv4")
result = self.library.Cli_SetConnectionParams(self.pointer, ip_address.encode(),
c_uint16(tsap_snap7),
c_uint16(tsap_logo))
if result != 0:
raise Snap7Exception("The parameter was invalid")
[docs] def set_connection_type(self, connection_type: int):
"""Sets the connection resource type, i.e the way in which the Clients
connects to a PLC.
Args:
connection_type: 1 for PG, 2 for OP, 3 to 10 for S7 Basic
Raises:
:obj:`Snap7Exception`: if the snap7 error code is diferent from 0.
"""
result = self.library.Cli_SetConnectionType(self.pointer,
c_uint16(connection_type))
if result != 0:
raise Snap7Exception("The parameter was invalid")
[docs] def get_connected(self) -> bool:
"""Returns the connection status
Notes:
This function has a bug, that returns `True` when the connection
is lost. This comes from the original `snap7 library`.
Returns:
True if connected.
"""
connected = c_int32()
result = self.library.Cli_GetConnected(self.pointer, byref(connected))
check_error(result, context="client")
return bool(connected)
[docs] def set_param(self, number: int, value):
"""Sets an internal Server object parameter.
Args:
number: Parameter type number
value: Parameter value
Returns:
Error code from snap7 library.
"""
logger.debug(f"setting param number {number} to {value}")
type_ = param_types[number]
result = self.library.Cli_SetParam(self.pointer, number, byref(type_(value)))
check_error(result, context="client")
return result
[docs] def get_param(self, number) -> int:
"""Reads an internal Logo object parameter.
Args:
number: Parameter type number
Returns:
Parameter value
"""
logger.debug(f"retreiving param number {number}")
type_ = param_types[number]
value = type_()
code = self.library.Cli_GetParam(self.pointer, c_int(number),
byref(value))
check_error(code)
return value.value