Modbus not getting any values except Zeros

I am using a robodyn mega 2560 with embedded wiznet5500 chip.
I am trying to communicate with an acromag io expander 963EN-4012 via Modbus TCP/IP.
I am building off of an existing Modbus tcpIP client example from the ArduinoModbus Library.
I am trying to read the holding register for the first analog input. When I load this code I do connect to the acromag, however no matter if I connect a thermocouple to the analog input or not I Just read zeros in the serial monitor.
Am i doing something obviously wrong here.
Any insight would be greatly appreciated.
Here is my code.

#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[] = {
  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED
IPAddress ip(128, 1, 1, 110); //needs to be a similar mask b/c will not connect
//IPAddress ip(192 , 168, 1, 110);

EthernetClient ethClient;
ModbusTCPClient modbusTCPClient(ethClient);

IPAddress server(128,1,1,100); // update with the IP Address of your Modbus server
//IPAddress server(192,168,1,100);

void setup() {
  //Initialize serial and wait for port to open:
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  pinMode(7, OUTPUT );
  digitalWrite(7, HIGH);//reseting ethernet wiznet5500

  // 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.********************");


void loop() {
  if(!modbusTCPClient.connected()) {
    // client not connected, start the Modbus TCP client
    Serial.println("Attempting to connect to Modbus TCP server");
    if (!modbusTCPClient.begin(server, 502)) {
      Serial.println("Modbus TCP Client failed to connect!");
    } else {
      Serial.println("Modbus TCP Client connected");
  else {



Here is datasheet for acromag.,-407,696

According to the manual, the device doesn't have any register on address 3010. As there is no indication of what you expected to read/write there, I cannot tell you what address to use.

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