import serial
import modbus_tk
import modbus_tk.defines as cst
from modbus_tk import modbus_rtu
import time
def ModbusRTU_Slave():
try:
# 设定串口为从站
# 外置参数包括端口 port = "COM3" 波特率:9600
server= modbus_rtu.RtuServer(serial.Serial(port="com3",baudrate=9600, bytesize=8, parity='N', stopbits=1))
server.start()
print("runing...")
SLAVE1 = server.add_slave(1)
SLAVE1.add_block('A', cst.HOLDING_REGISTERS, 0, 4) # 地址0,长度4
increase_num = 17000
for i in range(300):
SLAVE1.set_values('A', 0, [17000, i + 1, i + 2]) # 改变在地址0处的寄存器的值
time.sleep(0.1)
for i in range(1500):
increase_num = increase_num - 1
SLAVE1.set_values('A', 0, [increase_num, i + 1, i + 2]) # 改变在地址0处的寄存器的值
time.sleep(0.1)
for i in range(800):
SLAVE1.set_values('A', 0, [10000, i + 1, i + 2]) # 改变在地址0处的寄存器的值
time.sleep(0.1)
for i in range(800):
SLAVE1.set_values('A', 0, [17000, i + 1, i + 2]) # 改变在地址0处的寄存器的值
time.sleep(0.1)
except Exception as exc:
print(str(exc))
# 数据接收端
def ModbusRTU_Master():
try:
# 设定串口为从站
# 外置参数包括端口 port = "COM3" 波特率:9600
master = modbus_rtu.RtuMaster(serial.Serial(port="com4",baudrate=9600, bytesize=8, parity='N', stopbits=1))
master.set_timeout(1.0)
master.set_verbose(True)
# 读保持寄存器
read = master.execute(1, cst.HOLDING_REGISTERS, 0, 4) # 这里可以修改需要读取的功能码
print(red)
except Exception as exc:
print(str(exc))
功能代码cst
1~255中1~21是常用的,以下是读写专用的功能码
READ_COILS = 01 读线圈,位操作
READ_DISCRETE_INPUTS = 02 读离散输入状态,位操作
READ_HOLDING_REGISTERS = 03 读保持寄存器,字操作
READ_INPUT_REGISTERS = 04 读输入寄存器,字操作
WRITE_SINGLE_COIL = 05 写单线圈,位操作
WRITE_SINGLE_REGISTER = 06 写单一寄存器,字操作
WRITE_MULTIPLE_COILS = 15 写多个线圈【强制多点线圈】,位操作
WRITE_MULTIPLE_REGISTERS = 16 写多寄存器【写乘法寄存器】,字操作