Example of protocol with TRG-STA-GRS command cycle The initialization and reconnection of the communication is described in the chapter before. In order to initialize the communication, the MS toggles the Sync flag between 0 and 1 with cycle duration of 500 ms. Once the SC recognizes the Sync flag, it answers with an ACK frame of the same value as the detected Sync flag. The command STA is set to 2 (STA(02)) by the SC to request continuous status information. Hereupon, the MS sends its state with every answer. A prerequisite to accept commands by the MS is STA(01) (reply code from halm MS) and TOK(01). Direction Command code Reply Code Flag Remark SC → MS STA(02),TRG(01) Trigger a measurement * MS → SC Handshake acknowledge MS → SC STA(01), TRG(01) Trigger accepted SC → MS Handshake acknowledge SC → MS STA(02), TRG(FF) Command completed MS → SC Handshake acknowledge MS → SC TRG(FF), STA(02) TOK(FF) Reply completed, MS busy, cell transport not allowed SC → MS Handshake acknowledge MS → SC STA(02) TOK(01) Cell transport allowed SC → MS Handshake acknowledge MS → SC STA(01) RES(01) Measurement result data available SC → MS Handshake acknowledge SC → MS STA(02), GRS(01) MS → SC Handshake acknowledge MS → SC STA(01), GRS(01) RES(FF) Including result data SC → MS Handshake acknowledge SC → MS STA(02), GRS(FF) Command completed MS → SC Handshake acknowledge MS → SC STA(01), GRS(FF) Reply completed SC → MS Handshake acknowledge * SC sends TWO commands within one frame. In consequence, MS will reply with TWO answers. Same procedure for THREE commands. Please always send STA(02) together with every command. Do not send STA(FF) which will stop MS sending status and results.根据这个协议，帮我写一份UDP通讯的demo

好的，这里是一份简单的基于UDP通讯的TRG-STA-GRS命令循环协议的demo，希望能对您有所帮助。

import socket
import struct
import time

# 定义UDP通讯参数
UDP_IP = "192.168.0.1"  # MS设备IP地址
UDP_PORT = 5005  # MS设备接收数据的端口号

# 创建UDP通讯对象
sock = socket.socket(socket.AF_INET,  # Internet
                     socket.SOCK_DGRAM)  # UDP

# 初始化通讯：MS设备发送Sync flag，SC设备返回ACK
for i in range(2):
    sync_flag = i % 2  # Sync flag为0或1
    data = struct.pack('B', sync_flag)  # 打包Sync flag数据
    sock.sendto(data, (UDP_IP, UDP_PORT))
    print('发送Sync flag:', sync_flag)
    time.sleep(0.5)  # 延时500ms
    data, addr = sock.recvfrom(1024)  # 接收ACK
    ack_flag = struct.unpack('B', data)[0]  # 解包ACK flag数据
    print('收到ACK flag:', ack_flag)

# 发送TRG-STA-GRS命令循环
while True:
    # 命令1：TRG(01), STA(02)
    cmd1 = b'\x01\x02'  # TRG(01), STA(02)
    data = struct.pack('2s', cmd1)  # 打包命令1数据
    sock.sendto(data, (UDP_IP, UDP_PORT))
    print('发送命令1：TRG(01), STA(02)')
    data, addr = sock.recvfrom(1024)  # 接收回复
    reply1 = struct.unpack('2B', data)  # 解包命令1的回复数据
    print('收到命令1的回复：', reply1)

    # 命令2：TRG(FF), STA(02)
    cmd2 = b'\xFF\x02'  # TRG(FF), STA(02)
    data = struct.pack('2s', cmd2)  # 打包命令2数据
    sock.sendto(data, (UDP_IP, UDP_PORT))
    print('发送命令2：TRG(FF), STA(02)')
    data, addr = sock.recvfrom(1024)  # 接收回复
    reply2 = struct.unpack('2B', data)  # 解包命令2的回复数据
    print('收到命令2的回复：', reply2)

    # 命令3：GRS(01), STA(02)
    cmd3 = b'\x02\x01'  # GRS(01), STA(02)
    data = struct.pack('2s', cmd3)  # 打包命令3数据
    sock.sendto(data, (UDP_IP, UDP_PORT))
    print('发送命令3：GRS(01), STA(02)')
    data, addr = sock.recvfrom(1024)  # 接收回复
    reply3 = struct.unpack('2B', data)  # 解包命令3的回复数据
    print('收到命令3的回复：', reply3)

    # 判断是否需要继续命令循环
    if reply2[1] == 0xFF:  # 如果命令2回复为TRG(FF), STA(02)，则退出循环
        break

# 关闭UDP通讯对象
sock.close()

以上代码仅供参考，具体实现需要根据您的具体需求进行修改。注意，这里的demo仅实现了命令循环的基本功能，如果需要实现更多的功能，还需要根据协议进行相应的扩展。