scanModbus

#!/usr/bin/env python3
import socket
import struct
from time import sleep
import sys,os

ip = "192.168.1.7"
port = 502

unit_id = 1
start_reg = 4607
count = 16

transaction_id = 1
protocol_id = 0
length = 6
function_code = 4

pkt = struct.pack(
    ">HHHBBHH",
    transaction_id,
    protocol_id,
    length,
    unit_id,
    function_code,
    start_reg,
    count
)

with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
    s.connect((ip, port))
    s.sendall(pkt)
    resp = s.recv(1024)

print("Raw response:", resp.hex())

if len(resp) < 9:
    raise SystemExit("Short response")

if resp[7] == 0x84:
    print(f"Modbus exception code: 0x{resp[8]:02X}")
    raise SystemExit

byte_count = resp[8]
data = resp[9:9 + byte_count]

registers = [struct.unpack(">H", data[i:i+2])[0] for i in range(0, len(data), 2)]
while True:
    for i, value in enumerate(registers):
        print(f"304{608 + i:03d}: {value} (0x{value:04X})")
    sleep(0.5)
    os.system('clear')


""""
is D516,518 bogus? ??
"""