Converts Modbus Register Integers into Siemens TotalType data type

SiemensTotalType.js

function toTotalType(number_1, number_2, decimal_1, decimal_2){
    const number = (makeTwosComplement32BitInt(
        numberTo16BitBinary(number_1),
        numberTo16BitBinary(number_2)
    ));
    const decimal = (makeTwosComplement32BitInt(
        numberTo16BitBinary(decimal_1),
        numberTo16BitBinary(decimal_2)
    ));
    return number + decimal / 1000000000
}

function numberTo16BitBinary(num){
    const binString = ("0".repeat(16) + num.toString(2)).slice(-16);
    return binString;
}

function binary16BitToNumber(binRep){
    const intRep = parseInt(binRep, 2);
    return intRep;
}

function makeBinaryStringFrom32BitInt(intVal){
    const bin32 = ("0".repeat(32) + intVal.toString(2)).slice(-32);
    return [ bin32.substr(0,16), bin32.substr(16,16) ]
}

function makeTwosComplement32BitInt(high, low){
    const combined = high + low;
    let intVal = parseInt(combined, 2);
    if (high[0] === "1"){
        let twosString = [];
        for(let bit in combined){
            const newBit = combined[bit] === "0" ? 1 : 0;
            twosString.push(newBit)
        }
        intVal = -1 * (parseInt(twosString.join(""), 2) + 1);
    }
    return intVal;
}

console.log(toTotalType(65535, 65534, 4577, 41728));