This document can save you time. It is for integrating in custom linux applications.
Tested on linuxcnc 2.8 with debian 64bit stretch with builbot reprository set for update to master :
In some linuxcnc versions you have to be member of usergroup plugdevs and serial to get sudo acces to read i/o.
How to become a member of those groups, is a matter of googling. In linux mint it is very easy to select this groups.
Code:
#MODBUS this section must be above everything in your code.
from __future__ import division
#/MODBUS
#MODBUS
import pymodbus
import serial
from pymodbus.pdu import ModbusRequest
from pymodbus.client.sync import ModbusSerialClient as ModbusClient #initialize a serial RTU client instance
from pymodbus.transaction import ModbusRtuFramer
from pymodbus.constants import Endian # Nodig voor 32-bit float getallen (2 registers / 4 bytes)
from pymodbus.payload import BinaryPayloadDecoder # Nodig voor 32-bit float getallen (2 registers / 4 bytes)
from pymodbus.payload import BinaryPayloadBuilder # Nodig om 32-bit floats te schrijven naar register
from pymodbus.payload import BinaryPayloadBuilder, BinaryPayloadDecoder
method = "rtu"
port = "/dev/ttyUSB0"
baudrate = 9600
stopbits = 1
bytesize = 8
parity = "N"
timeout = 0.01
retries = 2
client = ModbusClient(method = method, port = port, stopbits = stopbits, bytesize = bytesize, parity = parity, baudrate = baudrate, timeout = timeout, retries = retries)
#connection = client.connect()
#/MODBUS
#Glade button example
def on_modbus_tool_pressed(self, widget, data=None):
connection = client.connect()
print connection
y = 10 #10 volt
client.write_register(0, float(4095 / 10) * y, unit=1)
client.close()
connection = client.connect()
print connection
b = 8 #8 volt
client.write_register(1, float(4095 / 10) * b, unit=1)
client.close()
connection = client.connect()
print connection
client.write_coil(0, True)
client.write_coil(1, True)
client.write_coil(2, True)
client.write_coil(3, True)
client.close()
connection = client.connect()
print connection
client.write_coil(0, False)
client.write_coil(1, False)
client.write_coil(2, False)
client.write_coil(3, False)
client.close()
connection = client.connect()
print connection
analog_input = client.read_input_registers(0, 4, unit=1)
print data
print "value_0:", analog_input.registers[0]
print "value_1:", analog_input.registers[1]
print "value_2:", analog_input.registers[2]
print "value_3:", analog_input.registers[3]
client.close()
connection = client.connect()
print connection
digital_input = client.read_discrete_inputs(0, 4, unit=1)
print data
print "value_0:", digital_input.bits[0]
print "value_1:", digital_input.bits[1]
print "value_2:", digital_input.bits[2]
print "value_3:", digital_input.bits[3]
client.close()
