ID number seems not to work for modbus TCP server

[HollyGates]

Hi there. I have gotten this library running with a modified example. My ESP32 is a modbus TCP server and is getting polled from my PC using SimplyModbus software. This seems to work ok, but the code doesn't seem to care what modbus slave ID I ask for, it responds the same all the time.

In my application I need to do different things depending on which slave ID comes in with the modbus TCP query. Is there a way to do this?

I tried adding an argument to the modbusTCPServer.begin call, like this modbusTCPServer.begin(5), but it still responds to all slave IDs.

Here is my code:

/*
  Ethernet Modbus TCP Client Toggle

  This sketch toggles the coil of a Modbus TCP server connected
  on and off every second.

  Circuit:
   - Any Arduino MKR Board
   - MKR ETH Shield

  created 16 July 2018
  by Sandeep Mistry
*/

#define SERIAL_PORT_HARDWARE Serial

#include <SPI.h>
#include <Ethernet.h>
#include <ArduinoRS485.h> // ArduinoModbus depends on the ArduinoRS485 library
#include <ArduinoModbus.h>

// Enter a MAC address for your controller below.
// Newer Ethernet shields have a MAC address printed on a sticker on the shield
// The IP address will be dependent on your local network:
byte mac[] = {
  0x98, 0x76, 0xB6, 0x11, 0x85, 0x82
};
IPAddress ip(10, 0, 6, 75);

EthernetServer ethServer(502);

ModbusTCPServer modbusTCPServer;

void updateLED() {
  // read the current value of the coil
  int coilValue = modbusTCPServer.coilRead(0x00);

  if (coilValue) {
    // coil value set, turn LED on
    digitalWrite(BUILTIN_LED, HIGH);
  } else {
    // coild value clear, turn LED off
    digitalWrite(BUILTIN_LED, LOW);
  }
}

void setup() {
  // You can use Ethernet.init(pin) to configure the CS pin
  //Ethernet.init(10);  // Most Arduino shields
  //Ethernet.init(5);   // MKR ETH shield
  //Ethernet.init(0);   // Teensy 2.0
  //Ethernet.init(20);  // Teensy++ 2.0
  //Ethernet.init(15);  // ESP8266 with Adafruit Featherwing Ethernet
  Ethernet.init(33);  // ESP32 with Adafruit Featherwing Ethernet

  // Open serial communications and wait for port to open:
  Serial.begin(9600);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }
  Serial.println("Ethernet Modbus TCP Example");

  // start the Ethernet connection and the server:
  Ethernet.begin(mac, ip);

  // Check for Ethernet hardware present
  if (Ethernet.hardwareStatus() == EthernetNoHardware) {
    Serial.println("Ethernet shield was not found.  Sorry, can't run without hardware. :(");
    while (true) {
      delay(1); // do nothing, no point running without Ethernet hardware
    }
  }
  if (Ethernet.linkStatus() == LinkOFF) {
    Serial.println("Ethernet cable is not connected.");
  }

  // start the server
  ethServer.begin();
  
  // start the Modbus TCP server
  if (!modbusTCPServer.begin(5)) {
    Serial.println("Failed to start Modbus TCP Server!");
    while (1);
  }

  // configure the LED
  pinMode(BUILTIN_LED, OUTPUT);
  digitalWrite(BUILTIN_LED, LOW);

  // configure a single coil at address 0x00
  modbusTCPServer.configureCoils(0x00, 1);
  modbusTCPServer.configureHoldingRegisters(100,10);
}

void loop() {
  // listen for incoming clients
  EthernetClient client = ethServer.available();
  
  if (client) {
    // a new client connected
    Serial.println("new client");

    // let the Modbus TCP accept the connection 
    modbusTCPServer.accept(client);

    while (client.connected()) {
      // poll for Modbus TCP requests, while client connected
      modbusTCPServer.poll();

      // update the LED
      updateLED();
    }

    Serial.println("client disconnected");
  }
}