modbus_tk ：完整modbus协议栈的实现，支持modbus tcp/rtu｛1.提供slave模拟器，即模拟modbus server:502), web-based hmi master支持｝
modbus协议举例简解：
例：发送：01 03 00 10 00 04 crc1 crc2
01 地址
03 功能码（读）
00 10 起始地址
00 04 起始地址往后多少位
crc1 crc2 CRC校验码
接受：01 03 08 xx1 xx2 xx3 xx4 xx5 xx6 xx7 xx8 crc1 crc2
01 03:与发送一致
08: 数据的长度
xx1 xx2 xx3 xx4 xx5 xx6 xx7 xx8:读取的长度*2
crc1 crc2:CRC校验码
python 实现modbus RTU slave
import sys
import modbus_tk
import struct
import modbus_tk.defines as cst
from modbus_tk import modbus_rtu
import time
import serial
import threading
PORT = 'com3'
#PORT = '/dev/ptyp5'
def main():
"""main"""
global slave_1
logger = modbus_tk.utils.create_logger(name="console", record_format="%(message)s")
#Create the server
server = modbus_rtu.RtuServer(serial.Serial(PORT))
try:
logger.info("running...")
logger.info("enter 'quit' for closing the server")
server.start()
slave_1 = server.add_slave(1)
slave_1.add_block('0', cst.HOLDING_REGISTERS, 0, 100)
t = threading.Thread(target=updateData)
t.setDaemon(True)
t.start()
while True:
cmd = sys.stdin.readline()
args = cmd.split(' ')
if cmd.find('quit') == 0:
sys.stdout.write('bye-bye\r\n')
break
elif args[0] == 'add_slave':
slave_id = int(args[1])
server.add_slave(slave_id)
sys.stdout.write('done: slave %d added\r\n' % (slave_id))
elif args[0] == 'add_block':
slave_id = int(args[1])
name = args[2]
block_type = int(args[3])
starting_address = int(args[4])
length = int(args[5])
slave = server.get_slave(slave_id)
slave.add_block(name, block_type, starting_address, length)
sys.stdout.write('done: block %s added\r\n' % (name))
elif args[0] == 'set_values':
slave_id = int(args[1])
name = args[2]
address = int(args[3])
values = []
for val in args[4:]:
values.append(int(val))
slave = server.get_slave(slave_id)
slave.set_values(name, address, values)
values = slave.get_values(name, address, len(values))
sys.stdout.write('done: values written: %s\r\n' % (str(values)))
elif args[0] == 'get_values':
slave_id = int(args[1])
name = args[2]
address = int(args[3])
length = int(args[4])
slave = server.get_slave(slave_id)
values = slave.get_values(name, address, length)
sys.stdout.write('done: values read: %s\r\n' % (str(values)))
else:
sys.stdout.write("unknown command %s\r\n" % (args[0]))
finally:
server.stop()
#更新值
def updateData():
global slave_1
while True:
slave_1.set_values('0', 3, 88)
slave_1.set_values('0', 4, 99)
# print(slave_1.get_values('0',3,2))
time.sleep(1)
if __name__ == "__main__":
main()
python 实现 modbus TCP slave
import sys
import modbus_tk
import modbus_tk.defines as cst
from modbus_tk import modbus_tcp
def main():
"""main"""
logger = modbus_tk.utils.create_logger(name="console", record_format="%(message)s")
try:
#Create the server
server = modbus_tcp.TcpServer()
logger.info("running...")
logger.info("enter 'quit' for closing the server")
server.start()
slave_1 = server.add_slave(1)
slave_1.add_block('0', cst.HOLDING_REGISTERS, 0, 100)
while True:
cmd = sys.stdin.readline()
args = cmd.split(' ')
if cmd.find('quit') == 0:
sys.stdout.write('bye-bye\r\n')
break
elif args[0] == 'add_slave':
slave_id = int(args[1])
server.add_slave(slave_id)
sys.stdout.write('done: slave %d added\r\n' % slave_id)
elif args[0] == 'add_block':
slave_id = int(args[1])
name = args[2]
block_type = int(args[3])
starting_address = int(args[4])
length = int(args[5])
slave = server.get_slave(slave_id)
slave.add_block(name, block_type, starting_address, length)
sys.stdout.write('done: block %s added\r\n' % name)
elif args[0] == 'set_values':
slave_id = int(args[1])
name = args[2]
address = int(args[3])
values = []
for val in args[4:]:
values.append(int(val))
slave = server.get_slave(slave_id)
slave.set_values(name, address, values)
values = slave.get_values(name, address, len(values))
sys.stdout.write('done: values written: %s\r\n' % str(values))
elif args[0] == 'get_values':
slave_id = int(args[1])
name = args[2]
address = int(args[3])
length = int(args[4])
slave = server.get_slave(slave_id)
values = slave.get_values(name, address, length)
sys.stdout.write('done: values read: %s\r\n' % str(values))
else:
sys.stdout.write("unknown command %s\r\n" % args[0])
finally:
server.stop()
if __name__ == "__main__":
main()
总结：
这里用python实现了modbus slave,实现modbus master也可以用modbus_tk实现,后续贴出实现modbus master代码。