Need Help getting Modbus to work

Using Arduino Networking, Protocols, and Devices
1

So I am using the Arduino MKR 1010 board along with a Arduino MKR RS485 shield in order to make the arduino communicate using Modbus. My goal it to set the Arduino board as a slave and have it communicate with a PLC. However I can no seem to get the communication between the two connected. I have tried using different cables and even a different arduino (MKR Zero). I have tried many different library example codes such as ARDUINO485, ModbusRTUSlave and ModbusRTUMaster. I have the code that I have most recently been working with in this post. Any help would be greatly appreciated!

#include <ArduinoRS485.h>
#include <ArduinoModbus.h>

uint16_t TEST = 40;
int packetReceived;

void setup() {
  Serial.begin(9600);
  

  // start the Modbus RTU server, with slave id 1
  if (!ModbusRTUServer.begin(1, 19200, SERIAL_8E1)) {
    Serial.println("Failed to start Modbus RTU Server!");
    while (1);
  }

  // configure a group of holding registers
  ModbusRTUServer.configureHoldingRegisters(53249,100);
  // Writes to a single holding register
  ModbusRTUServer.holdingRegisterWrite(53249, TEST);
  ModbusRTUServer.holdingRegisterWrite(53250, TEST);
  ModbusRTUServer.holdingRegisterWrite(53251, TEST);
  
}

void loop() {
  
  // poll for Modbus RTU requests
  packetReceived = ModbusRTUServer.poll();

  if(packetReceived) {
    Serial.println("Request Received!");
  }
  else{
    Serial.println("No package Received!");
  }
  delay(100);
}