Hello, Thank you for your response.
I'm used minimalmodbus on my python script in the RPi . It's simple to imple,manting with my sripting level and works fine but only with in serial mode not in the rs-485.
I tryed now with arduino library Modbus-Master-Slave-for-Arduino. and with this i can retrive respnse but i haveit only sometimes. see the attachement 1.
This is the arduino code for test:
/**
* Modbus slave example 3:
* The purpose of this example is to link a data array
* from the Arduino to an external device through RS485.
*
* Recommended Modbus Master: QModbus
* http://qmodbus.sourceforge.net/
*/
#include <ModbusRtu.h>
// assign the Arduino pin that must be connected to RE-DE RS485 transceiver
#define TXEN 2
// data array for modbus network sharing
uint16_t au16data[16] = {
3, 1415, 9265, 4, 2, 7182, 28182, 8, 0, 0, 0, 0, 0, 0, 1, -1 };
/**
* Modbus object declaration
* u8id : node id = 0 for master, = 1..247 for slave
* u8serno : serial port (use 0 for Serial)
* u8txenpin : 0 for RS-232 and USB-FTDI
* or any pin number > 1 for RS-485
*/
Modbus slave(1,0,TXEN); // this is slave @1 and RS-485
void setup() {
slave.begin( 19200 ); // baud-rate at 19200
}
void loop() {
slave.poll( au16data, 16 );
}
and this is my python code on RPi for test:
#!usr/bin/env python
from math import pi,sqrt,acos
import subprocess
import time
import RPi.GPIO as GPIO
import urllib
import httplib
import minimalmodbus
import time
import serial
instrument = minimalmodbus.Instrument('/dev/ttyUSB0',1) # Nom du port et adresse modbus // port série de raspberry = ttyAMA0 // port usb = ttyUSB0
instrument2 = minimalmodbus.Instrument('/dev/ttyUSB0',2) # Nom du port et adresse modbus // port série de raspberry = ttyAMA0 // port usb = ttyUSB0
instrument.serial.baudrate = 19200
instrument.serial.bytesize = 8
instrument.serial.parity = serial.PARITY_NONE
instrument.serial.stopbits = 1
instrument.serial.timeout = 1 # secondes
instrument.mode = minimalmodbus.MODE_RTU # rtu ou ascii // MODE_ASCII ou MODE_RTU
instrument.debug = False
instrument.serial.xonxoff = True
instrument.serial.rtscts = False
instrument.serial.dsrdtr = False
minimalmodbus.CLOSE_PORT_AFTER_EACH_CALL = True
instrument2.serial.baudrate = 19200
instrument2.serial.bytesize = 8
instrument2.serial.parity = serial.PARITY_NONE
instrument2.serial.stopbits = 1
instrument2.serial.timeout = 1 # secondes
instrument2.mode = minimalmodbus.MODE_RTU # rtu ou ascii // MODE_ASCII ou MODE_RTU
instrument2.debug = False
instrument2.serial.xonxoff = True
instrument2.serial.rtscts = False
instrument2.serial.dsrdtr = False
usb1_on = True
usb2_on = True
if instrument.debug == True:
print instrument
# Lecture d'un registre
while 1:
if usb2_on == True :
try:
# test_reg = instrument.read_register(1,0)
# print test_reg
# test_reg = instrument.read_register(1,0)
# print test_reg
print "Registres de l'ID 1 USB"
test_reg = instrument2.read_registers(0,10,4) # lecture plusieurs registres,( registre de départ, nb de registres à lire (max 10), décimales)
print test_reg
# test_reg = instrument2.read_registers(0,2,3)
# print test_reg
time.sleep (0.05)
except:
print ("error USB1 -----------------------")
time.sleep (8)
if usb1_on == True :
try:
# test_reg = instrument.read_register(1,0)
# print test_reg
# test_reg = instrument.read_register(1,0)
# print test_reg
print "Registres de l'ID 2 USB"
test_reg = instrument.read_registers(0,10,4) # lecture plusieurs registres,( registre de départ, nb de registres à lire (max 10), décimales)
print test_reg
# test_reg = instrument.read_registers(10,10,4)
# print test_reg
time.sleep (0.05)
except:
print ("error usb 2 ------------------------------")
time.sleep (8)
tankyou another time to help me and sorry for my english i'm french boy
