node-red-contrib-dellmonitor/commands.js

RS232 over network control of a Dell CS5517H LCD Monitor

var sendHeader = [0x37, 0x51];
var receiveHeader = [0x6F, 0x37];

var getBit = 0xEB;
var setBit = 0xEA;

var commandSet = {
    "name": 0x01,
    "serialNumber": 0x02,
    "powerState": 0x20,
    "powerLED": 0x21,
    "powerUSB": 0x22,
    "resetPower": 0x2F,
    "brightness": 0x30,
    "contrast": 0x31,
    "sharpness": 0x34,
    "videoInputAutoSelect": 0x60,
    "videoInput": 0x62
};

var stateBits = {
    "off": [0x00],
    "on": [0x01]
};

var inputBits = {
    "HDMI1": [0x01, 0x00, 0x00, 0x00],
    "HDMI2": [0x02, 0x00, 0x00, 0x00],
    "DP1": [0x08, 0x00, 0x00, 0x00],
    "VGA1": [0x40, 0x00, 0x00, 0x00],
}

module.exports = {
    state: stateBits,
    inputs: inputBits,
    command: commandSet,

    //Send a request for status when something else changes the state
    generateRequestOnChange: function(message) {
        return generateRawCommand(0xEB, message[5]);
    },

    generateBuffer: function(direction, command, data) {
        switch(direction) {
            case "set": direction = setBit; break;
            case "get": direction = getBit; break;
            default: return "Incorrect Direction";
        }
        //Get command
        for(var key in commandSet) {
            if(key.toString().toLowerCase() == command.toString().toLowerCase()) {
                command = commandSet[key];
            }
        }
        //Set data
        if(data !== undefined && data !== null) {
            switch(command) {
                case commandSet.name: data = new Buffer(data); break;
                case commandSet.serialNumber: data = new Buffer(data); break;
                case commandSet.powerState:
                case commandSet.videoInputAutoSelect:
                case commandSet.powerLED:
                case commandSet.powerUSB:
                case commandSet.resetPower: data = [data == "on"]; break;
                case commandSet.brightness: data = [data];
                case commandSet.contrast: data = [data];
                case commandSet.sharpness: data = [data];
                case commandSet.videoInput: {
                    for(var key in inputBits) {
                        if(key.toString().toLowerCase() == data.toString().toLowerCase()) {
                            data = inputBits[key];
                        }
                    }
                    break;
                }
            }
        }

        var rawCommand = generateRawCommand(direction, command, data);
        return rawCommand;
    },
    generateRaw: generateRawCommand,

    isReceivedValid: function(message) {
        if(message[0] != receiveHeader[0]){return false;}
        if(message[1] != receiveHeader[1]){return false;}
        if(message[2] != (2 + getDataRaw(message).length)){return false;}
        if(message[3] != 0x02){return false;}
        var CRC = receiveHeader[0] ^ receiveHeader[1] ^ (2 + getDataRaw(message).length) ^ 0x02 ^ message[4];
        for(var i = 0; i < getDataRaw(message).length; i++) {
            CRC ^= getDataRaw(message)[i];
        }
        if(message[message.length - 1] != CRC){return false;}
        return true;
    },

    getResultCode: function(message) {
        switch(message[4]) {
            case 0x00: return "success";
            case 0x01: return "timeout";
            case 0x02: return "parametersError";
            case 0x03: return "notConnected";
            case 0x04: return "otherError";
        }
    },

    getCommand: getCommand,

    getData: function(message) {
        switch(message[5]) {
            case commandSet.name: {
                return message.slice(6, message.length -1).toString();
                break;
            }
            case commandSet.serialNumber: {
                return message.slice(6, message.length -1).toString();
                break;
            }
            case commandSet.powerState: {
                if(message[6] == stateBits.off){return "off";}
                else if(message[6] == stateBits.on){return "on";}
                break;
            }
            case commandSet.powerLED: {
                if(message[6] == stateBits.off){return "off";}
                else if(message[6] == stateBits.on){return "on";}
                break;
            }
            case commandSet.resetPower: {
                return undefined;
                break;
            }
            case commandSet.brightness: {
                return message[6];
                break;
            }
            case commandSet.contrast: {
                return message[6];
                break;
            }
            case commandSet.sharpness: {
                return message[6];
                break;
            }
            case commandSet.videoInputAutoSelect: {
                if(message[6] == stateBits.off){return "off";}
                else if(message[6] == stateBits.on){return "on";}
                break;
            }
            case commandSet.videoInput: {
                for(var key in inputBits) {
                    if(inputBits[key][0] == message[6]){return key.toString();}
                }
                break;
            }
        }
    }
}

//Get the friendly command
function getCommand(message) {
    //Get command
    for(var key in commandSet) {
        if(commandSet[key] == message[5]){return key;}
    }
}

//Get the raw data stream
function getDataRaw(message) {
    return message.slice(5, message.length -1);
}

//Generate the raw command
function generateRawCommand(readWriteBit, command, data) {
    //H1 H2 Length R/W Command Data CHK (Xor byte by byte)
    var buffer = new Buffer(5);
    var dataLength;
    if(data === undefined || data == null){dataLength = 0;}else{dataLength = data.length;}
    var CRC = sendHeader[0] ^ sendHeader[1] ^ (2 + dataLength) ^ readWriteBit ^ command;
    if(dataLength > 0) {
        for(var i = 0; i < data.length; i++) {
        CRC ^= data[i];
        }
    }

    buffer.writeUInt8(sendHeader[0], 0);
    buffer.writeUInt8(sendHeader[1], 1);
    buffer.writeInt8(2 + dataLength, 2);
    buffer.writeUInt8(readWriteBit, 3);
    buffer.writeUInt8(command, 4);
    if(dataLength > 0) {data = Buffer.from(data);}
    var CRCBuffer = new Buffer(1);
    CRCBuffer.writeUInt8(CRC);
    if(dataLength > 0){ 
        var finalBuffer = Buffer.concat([buffer, data, CRCBuffer]);
    }
    else {
        var finalBuffer = Buffer.concat([buffer, CRCBuffer]);
    }
    return finalBuffer;
}