Modbus serial implementation

Question

I'm trying to write registers using modbus-serial library. This is my code:

    const ModbusRTU = require("modbus-serial");
    
    const gatewayIpAddress = "XXX.XXX.XXX.XXX";
    const tcpPort = 502;
    const unitId = 1;
    
    const storePallet = async (shuttle) => {
        console.log("Storepallet function");
        console.log("ShuttleNumber: " + shuttle);
        const client = new ModbusRTU();
    
        try {
            await client.connectTCP(gatewayIpAddress, { port: tcpPort });
            console.log("Connected to Radioshuttle device over Modbus TCP");
    
            // Write store request
            await client.setID(unitId);
            await client.writeRegister(0, 1); // Address 0 represents tag #4 BIT 02.0.1
    
            console.log("Pallet stored successfully");
            client.close();
        } catch (error) {
            console.error("Error storing pallet:", error);
            client.close();
            throw error;
        }
    };
    
    storePallet(1).catch((error) => {
        // Handle the error here
        console.error("Unhandled error:", error);
    });

The problem is that the device is not responsive to this code, here is the documentation:

Set up of the connecting Modbus TCP Client (Master)
General
RS Gateway IP Address: XXX.XXX.XXX.XXX
TCP Port: 502
Unit ID / Slave address: 1
Read Radioshuttle output data.
Function code: 04 – Read Input Registers
Read Data Start address: 1
Read Data Size: 10
Write Radioshuttle input data.
Function code: 16 – Write Multiple Registers
Write Data Start address: 1
Write Data Size: 5

Registers - RS Input tags:

and for the store request:

Tag #	Format	Address	Name
4	BIT	002.0.1	Store request

Description:
Set to 1 by MCS to initiate the command: Store pallet in racking.
Set to 0 by MCS, when RS reply with RS Output tag # 5 set to 1.

Am I doing something wrong?

Answer 1

It seems that i have been working wrong with the registers, as simply changing the code to this for store pallet command worked:

 const ModbusRTU = require("modbus-serial");
    
    const gatewayIpAddress = "XXX.XXX.XXX.XXX";
    const tcpPort = 502;
    const unitId = 1;
    
    const storePallet = async (shuttle) => {
        console.log("Storepallet function");
        console.log("ShuttleNumber: " + shuttle);
        const client = new ModbusRTU();
    
        try {
            await client.connectTCP(gatewayIpAddress, { port: tcpPort });
            console.log("Connected to Radioshuttle device over Modbus TCP");
    
            // Write store request
            await client.setID(unitId);
            await client.writeRegister(1, 2);
    
            console.log("Pallet stored successfully");
            client.close();
        } catch (error) {
            console.error("Error storing pallet:", error);
            client.close();
            throw error;
        }
    };
    
    storePallet(1).catch((error) => {
        // Handle the error here
        console.error("Unhandled error:", error);
    });