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 (a.m.emelianov@gmail.com) https://github.com/emelianov/modbus-esp8266 /

ifdef ESP8266

include

else

include

endif

include

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?

[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

else

include

endif

include

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?

[wupeng1987824]

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 #else #include #endif #include

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?

change the read function to below: [unit] instead of your master slavId. default 255 mb.readHreg(remote, REG, &res,1,nullptr,1);