Modbus Client TCP

[Barone1968]

Thank you for the help you provide to all of us, I have a problem that certainly others have already solved, I use the TCP example client code that connects correctly with the Server, the Client on monitor always returns me 0 even if the value of the registers varies on the Server, my need is to read 10 registers from server t and have them individually available on the client.... example first register read = Var 1, second read on Var 2 etc. etc. can you help me thanks.

This is the code that USE

/*
Modbus-Arduino Example - Master Modbus IP Client (ESP8266/ESP32)
Read Holding Register from Server device
(c)2018 Alexander Emelianov ([e-mail])
https://github.com/emelianov/modbus-esp8266
*/

#ifdef ESP8266
#include <ESP8266WiFi.h>
#else
#include <WiFi.h>
#endif
#include <ModbusIP_ESP8266.h>

const int REG = 528; // Modbus Hreg Offset
IPAddress remote(192, 168, 199, 233); // Address of Modbus Slave device
const int LOOP_COUNT = 10;

ModbusIP mb; //ModbusIP object

void setup() {
Serial.begin(115200);

WiFi.begin("xxx", "111");

while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}

Serial.println("");
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());

mb.client();
}

uint16_t res = 0;
uint8_t show = LOOP_COUNT;

void loop() {
if (mb.isConnected(remote)) { // Check if connection to Modbus Slave is established
mb.readHreg(remote, REG, &res, 10); // Initiate Read Hregs from Modbus Server
} else {
mb.connect(remote); // Try to connect if no connection
}
mb.task(); // Common local Modbus task
delay(100); // Pulling interval
if (!show--) { // Display Slave register value one time per second (with default settings)
Serial.println(res);
show = LOOP_COUNT;
}
}

[ChangC2]

I also have the same issue while using the Modbus TCP client.
Read all values 0.
Did you find the reason and solution?

[Alexander Emelianov]

Try to use more complex example that will show error code.
https://github.com/emelianov/modbus-esp8266/blob/master/examples/Callback/Transactional/Transactional.ino

[ChangC2]

Thank you for your comment, Alexander Emelianov.
I used the sample you provided in this url,
https://github.com/emelianov/modbus-esp8266/blob/master/examples/TCP-ESP/client/client.ino.

#ifdef ESP8266
#include <ESP8266WiFi.h>
#else
#include <WiFi.h>
#endif
#include <ModbusIP_ESP8266.h>

const int REG = 528; // Modbus Hreg Offset
IPAddress remote(192, 168, 30, 13); // Address of Modbus Slave device
const int LOOP_COUNT = 10;

ModbusIP mb; //ModbusIP object

void setup() {
Serial.begin(115200);

WiFi.begin("SSID", "PASSWORD");

while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}

Serial.println("");
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());

mb.client();
}

uint16_t res = 0;
uint8_t show = LOOP_COUNT;

void loop() {
if (mb.isConnected(remote)) { // Check if connection to Modbus Slave is established
mb.readHreg(remote, REG, &res); // Initiate Read Coil from Modbus Slave
} else {
mb.connect(remote); // Try to connect if no connection
}
mb.task(); // Common local Modbus task
delay(100); // Pulling interval
if (!show--) { // Display Slave register value one time per second (with default settings)
Serial.println(res);
show = LOOP_COUNT;
}
}

I tested with the EasyModbusTCP Server Simulator.
When I test the sample, success to connect to server.
but when I read the hreg, it always get the Zero.
Could you provide the sample code that can read the href correctly?