为什么一个单纯的modbus通讯协议运行显示字节超出索引范围，采用官网的案例也运行不成功

[46fz]

import time
from pyb import UART
from modbus import ModbusRTU
uart = UART(3,115200, parity=None, stop=2, timeout=1, timeout_char=4)
modbus = ModbusRTU(uart, register_num=9999)

while(True):
    if modbus.any():
        modbus.handle(debug=True)
    else:
        time.sleep_ms(100)
        modbus.REGISTER[0] = 1000
        modbus.REGISTER[1] += 1
        modbus.REGISTER[3] += 3
        #print(modbus.REGISTER[10:15])
        # image processing in there
        

[kidswong999]

使用的是西门子PLC，S7-200吗？https://singtown.com/learn/50806/

[z5l4]

@46fz
＋＝，运行时间长了肯定会超，到一个数值给他清零