Skip to content

Instantly share code, notes, and snippets.

Created April 28, 2017 19:01
  • Star 0 You must be signed in to star a gist
  • Fork 0 You must be signed in to fork a gist
Star You must be signed in to star a gist
Save muttiopenbts/27ec73f16980ecda4b7586813167c05d to your computer and use it in GitHub Desktop.
Test script for interacting with device over modbus-rtc.
Need to improve received strings to output correctly after decoding.
import pymodbus
import serial
from pymodbus.constants import Endian
from pymodbus.pdu import ModbusRequest
from pymodbus.client.sync import ModbusSerialClient as ModbusClient #initialize a serial RTU client instance
from pymodbus.transaction import ModbusRtuFramer
import logging
from pymodbus.payload import BinaryPayloadDecoder
from pymodbus.payload import BinaryPayloadBuilder
import hexdump
log = logging.getLogger()
#usb_device = '/dev/tty.wchusbserial1420'
usb_device = '/dev/tty.usbserial-AL00KDH2'
#count= the number of registers to read
#unit= the slave unit this request is targeting
#address= the starting address to read from
client= ModbusClient(method = "rtu", port=usb_device,stopbits = 1, bytesize = 8, parity = 'N', baudrate= 9600, timeout=3, reconnects=2)
#Connect to the serial modbus server
connection = client.connect()
print connection
reg = 101
num_of_reg = 8
#Starting add, num of reg to read, slave unit.
result = client.read_input_registers(reg, num_of_reg, unit=0x18) # address, count, slave address
if result and hasattr(result, 'registers'):
decoder = BinaryPayloadDecoder.fromRegisters(result.registers, endian=Endian.Little)
decoded = {
'raw': result.registers,
'string8': decoder.decode_string(8),
'string16': decoder.decode_string(16),
'string32': decoder.decode_string(32),
# 'float': decoder.decode_32bit_float(),
# '16uint': decoder.decode_16bit_uint(),
# '8int': decoder.decode_8bit_int(),
# 'bits': decoder.decode_bits(),
print "-" * 60
print "Decoded Data"
print "-" * 60
for name, value in decoded.iteritems():
print ("%s\t" % name), value
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment