gateway_plc/gateway/snap7_client.py

import snap7
import logging
from threading import Lock
import time
from snap7.util import *
import ast

class Snap7Client:
    """Snap7客户端，处理与PLC的通信"""

    def __init__(self, ip, rack, slot, max_retries=5, retry_base_delay=1):
        """
        初始化Snap7客户端

        Args:
            ip: PLC IP地址
            rack: Rack编号
            slot: Slot编号
            max_retries: 最大重试次数
            retry_base_delay: 基础重试延迟（秒）
        """
        self.ip = ip
        self.rack = rack
        self.slot = slot
        self.client = snap7.client.Client()
        self.lock = Lock()
        self.connected = False
        self.max_retries = max_retries
        self.retry_base_delay = retry_base_delay
        self.last_connect_attempt = 0
        self.retry_count = 0
        self.logger = logging.getLogger(f"Snap7Client[{ip}]")

    def is_valid_connection(self):
        """检查连接是否真正有效"""
        try:
            # 尝试读取PLC的运行状态
            cpu_state = self.client.get_cpu_state()
            print("当前 CPU 状态:", cpu_state)
            return cpu_state in ['S7CpuStatusRun', 'S7CpuStatusStop']
        except:
            return False

    def connect(self):
        """建立与PLC的连接并验证"""
        current_time = time.time()
        # 指数退避重试
        if self.retry_count > 0:
            delay = min(self.retry_base_delay * (2 ** (self.retry_count - 1)), 30)
            if current_time - self.last_connect_attempt < delay:
                return False  # 未到重试时间

        self.last_connect_attempt = current_time
        try:
            self.client.connect(self.ip, self.rack, self.slot)

            # 验证连接是否真正有效
            if self.client.get_connected() and self.is_valid_connection():
                self.connected = True
                self.retry_count = 0  # 重置重试计数
                self.logger.info(f"Successfully connected to PLC {self.ip}")
                return True
            else:
                self.connected = False
                self.logger.warning(f"Connection to {self.ip} established but PLC is not responding")
                try:
                    self.client.disconnect()
                except:
                    pass
                return False
        except Exception as e:
            self.retry_count = min(self.retry_count + 1, self.max_retries)
            self.logger.error(f"Connection to {self.ip} failed (attempt {self.retry_count}/{self.max_retries}): {e}")
            self.connected = False
            return False

    def read_db(self, db_number, offset, size):
        """
        从DB块读取数据

        Args:
            db_number: DB编号
            offset: 起始偏移量
            size: 读取字节数

        Returns:
            bytearray: 读取的数据，如果失败返回None
        """
        if not self.connected and not self.connect():
            self.logger.warning(f"Read failed: not connected to {self.ip}")
            return None  # 返回None而不是零填充数据

        try:
            with self.lock:   # 进入锁，其他线程需等待
                data = self.client.db_read(db_number, offset, size)
                # 验证返回数据的有效性
                if data is None or len(data) != size:
                    self.connected = False
                    self.logger.error(f"Read DB{db_number} returned invalid data size (expected {size}, got {len(data) if data else 0})")
                    return None
                return data
        except Exception as e:
            self.logger.error(f"Read DB{db_number} error: {e}")
            self.connected = False
            return None

    def read_db_bool(self, db_number, offset, bit_length):
        """
        从 DB 块中读取一个字节，并提取其中的多个 BOOL 位

        Args:
            db_number (int): DB块编号
            offset (int): 要读取的字节偏移地址
            bit_length: 第几位，如1，表示第1位

        Returns:
            result:返回位值
        """
        if not self.connected and not self.connect():
            self.logger.warning(f"Read failed: not connected to {self.ip}")
            return None  # 返回None而不是零填充数据

        try:
            with self.lock:
                data = self.client.db_read(db_number, offset, 1)
                result = {}

                for bit in range(bit_length):
                    result[bit] = bool(data[0] & (1 << bit))

                if result is None or len(result) != bit_length:
                    self.connected = False
                    self.logger.error(f"Read DB{db_number} returned invalid data size (expected {bit_length}, got {len(result) if data else 0})")
                    return None
                return result
        except Exception as e:
            self.logger.error(f"Read DB{db_number} error: {e}")
            self.connected = False
            return None

    def write_db(self, db_number, offset, data):
        """
        向DB块写入数据

        Args:
            db_number: DB编号
            offset: 起始偏移量
            data: 要写入的数据

        Returns:
            bool: 是否写入成功
        """
        if not self.connected and not self.connect():
            self.logger.warning(f"Write failed: not connected to {self.ip}")
            return False

        try:

            self.client.db_write(db_number, offset, data)
            self.logger.debug(f"Wrote {len(data)} bytes to DB{db_number} offset {offset}")
            return True
        except Exception as e:
            self.logger.error(f"Write DB{db_number} error: {e}")
            self.connected = False
            return False

    def batch_write_db(self, db_number, offset, data):
        """
        向DB块写入数据

        Args:
            db_number: DB编号
            offset: 起始偏移量
            data: 要写入的数据

        Returns:
            bool: 是否写入成功
        """
        if not self.connected and not self.connect():
            self.logger.warning(f"Write failed: not connected to {self.ip}")
            return False

        try:
            with self.lock:
                self.client.db_write(db_number, offset, data)
                self.logger.debug(f"Wrote {len(data)} bytes to DB{db_number} offset {offset}")
                return True
        except Exception as e:
            self.logger.error(f"Write DB{db_number} error: {e}")
            self.connected = False
            return False

    def write_db_bool(self, db_number, offset, data):
        """
        向DB块写入数据

        Args:
            db_number: DB编号
            offset: 起始偏移量
            data: 要写入的bool类型数据

        Returns:
            bool: 是否写入成功
        """
        if not self.connected and not self.connect():
            self.logger.warning(f"Write failed: not connected to {self.ip}")
            return False

        try:
            with self.lock:

                self.client.db_write(db_number, offset, data)
                self.logger.debug(f"Wrote {len(data)} bytes to DB{db_number} offset {offset}")
                return True
        except Exception as e:
            self.logger.error(f"Write DB{db_number} error: {e}")
            self.connected = False
            return False

    def batch_write_db_bool(self, db_number, offset, data):
        """
        向DB块写入数据

        Args:
            db_number: DB编号
            offset: 起始偏移量
            data: 要写入的bool类型数据

        Returns:
            bool: 是否写入成功
        """
        if not self.connected and not self.connect():
            self.logger.warning(f"Write failed: not connected to {self.ip}")
            return False

        try:
            with self.lock:
                print(db_number, offset, data)
                self.client.db_write(db_number, offset, data)
                self.logger.debug(f"Wrote {len(data)} bytes to DB{db_number} offset {offset}")
                return True
        except Exception as e:
            self.logger.error(f"Write DB{db_number} error: {e}")
            self.connected = False
            return False

    def read_generic(self, db_number, offset, data_type, count=1):
        """
        通用读取接口，支持多种数据类型
        Args:
            db_number: DB块编号
            offset: 起始偏移量（字节或位，对于bool类型）
            data_type: 数据类型 ('bool', 'byte', 'int', 'word', 'real', 'dint', 'dword')
            count: 要读取的数据个数
        Returns:
            解析后的数据（单个值或值列表），失败返回None
        """
        if not self.connected and not self.connect():
            self.logger.warning(f"Read failed: not connected to {self.ip}")
            return None

        try:
            if data_type == 'bool':
                # 对于bool，offset是位偏移
                byte_offset = offset // 8
                bit_offset = offset % 8
                # 计算需要读取的字节数
                last_bit = bit_offset + count - 1
                last_byte = last_bit // 8
                total_bytes = last_byte - byte_offset + 1

                # 读取原始字节数据
                data = self.read_db(db_number, byte_offset, total_bytes)
                if data is None:
                    return None

                # 解析bool值
                result = []
                for i in range(count):
                    current_bit = bit_offset + i
                    byte_idx = current_bit // 8
                    bit_idx = current_bit % 8
                    result.append(bool(data[byte_idx] & (1 << bit_idx)))

                return result[0] if count == 1 else result

            elif data_type == 'byte':
                data = self.read_db(db_number, offset, count)
                if data is None:
                    return None
                return [data[i] for i in range(count)] if count > 1 else data[0]

            elif data_type in ['int', 'word']:
                total_bytes = 2 * count
                data = self.read_db(db_number, offset, total_bytes)
                if data is None:
                    return None

                result = []
                for i in range(count):
                    if data_type == 'int':
                        result.append(get_int(data, i * 2))
                    else:  # word
                        result.append(get_word(data, i * 2))
                return result[0] if count == 1 else result

            elif data_type in ['dint', 'dword', 'real']:
                total_bytes = 4 * count
                data = self.read_db(db_number, offset, total_bytes)
                if data is None:
                    return None

                result = []
                for i in range(count):
                    if data_type == 'dint':
                        result.append(get_dint(data, i * 4))
                    elif data_type == 'dword':
                        result.append(get_dword(data, i * 4))
                    else:  # real
                        result.append(get_real(data, i * 4))
                return result[0] if count == 1 else result

            else:
                self.logger.error(f"Unsupported data type: {data_type}")
                return None

        except Exception as e:
            self.logger.error(f"Error reading {data_type} from DB{db_number} offset {offset}: {e}")
            return None

    def write_generic(self, db_number, offset, data_type, value):
        """
        通用写入接口，支持多种数据类型
        Args:
            db_number: DB块编号
            offset: 起始偏移量（字节或位，对于bool类型）
            data_type: 数据类型 ('bool', 'byte', 'int', 'word', 'real', 'dint', 'dword')
            value: 要写入的值（可以是单个值或列表）
        Returns:
            bool: 是否写入成功
        """
        if not self.connected and not self.connect():
            self.logger.warning(f"Write failed: not connected to {self.ip}")
            return False

        try:
            if data_type == 'bool':
                # 对于bool，offset是位偏移
                byte_offset = offset // 8
                bit_offset = offset % 8

                # 读取当前字节
                current_byte = self.read_db(db_number, byte_offset, 1)
                if current_byte is None:
                    return False

                # 修改特定位
                if isinstance(value, list):
                    # 多个bool值
                    for i, val in enumerate(value):
                        current_bit = bit_offset + i
                        byte_idx = current_bit // 8
                        bit_idx = current_bit % 8

                        if val:
                            current_byte[0] |= (1 << bit_idx)
                        else:
                            current_byte[0] &= ~(1 << bit_idx)
                else:
                    # 单个bool值
                    if value:
                        current_byte[0] |= (1 << bit_offset)
                    else:
                        current_byte[0] &= ~(1 << bit_offset)

                # 写回修改后的字节
                return self.write_db_bool(db_number, byte_offset, current_byte)

            elif data_type == 'byte':
                if isinstance(value, list):
                    # 批量写入
                    for i, val in enumerate(value):
                        if val < 0 or val > 255:
                            self.logger.error(f"Byte value out of range: {val}")
                            return False
                        if not self.write_db(db_number, offset + i, bytes([val])):
                            return False
                    return True
                else:
                    # 单个字节
                    if value < 0 or value > 255:
                        self.logger.error(f"Byte value out of range: {value}")
                        return False
                    return self.write_db(db_number, offset, bytes([value]))

            elif data_type in ['int', 'word']:
                if not isinstance(value, list):
                    value = [value]

                for i, val in enumerate(value):
                    # 确保int值在范围内
                    if data_type == 'int' and (val < -32768 or val > 32767):
                        self.logger.error(f"Int value out of range: {val}")
                        return False
                    elif data_type == 'word' and (val < 0 or val > 65535):
                        self.logger.error(f"Word value out of range: {val}")
                        return False

                    data = bytearray(2)
                    if data_type == 'int':
                        set_int(data, 0, val)
                    else:
                        set_word(data, 0, val)

                    if not self.write_db(db_number, offset + i * 2, data):
                        return False
                return True

            elif data_type in ['dint', 'dword', 'real']:
                if not isinstance(value, list):
                    value = [value]

                for i, val in enumerate(value):
                    data = bytearray(4)
                    if data_type == 'dint':
                        if val < -2147483648 or val > 2147483647:
                            self.logger.error(f"DInt value out of range: {val}")
                            return False
                        set_dint(data, 0, val)
                    elif data_type == 'dword':
                        if val < 0 or val > 4294967295:
                            self.logger.error(f"DWord value out of range: {val}")
                            return False
                        set_dword(data, 0, val)
                    else:  # real
                        set_real(data, 0, float(val))

                    if not self.write_db(db_number, offset + i * 4, data):
                        return False
                return True

            else:
                self.logger.error(f"Unsupported data type: {data_type}")
                return False

        except Exception as e:
            self.logger.error(f"Error writing {data_type} to DB{db_number} offset {offset}: {e}")
            return False