Why would you use the TCPClient? For single remote operation you could leave the socket open. I do something like this:

        var self = this;
        this.ip = a;
        this.Command = function(a){
            self.socket.write(a + "\r");
        };
        this.Command.Power = {};
        this.Command.Power.On = function(){
            self.Command("PWON");
        };
        this.Command.Power.Off = function(){
            self.Command("PWSTANDBY");
        };
        this.Command.Power.GetStatus = function(){
            self.Command("PW?");
        };
        this.Command.Power.Status = "";
        this.socket = new TCPSocket(false);
        this.socket.connect(self.ip, 23, 3000);
        this.socket.Reconnect = function(){
            self.socket = new TCPSocket(false);
            self.socket.connect(self.ip, 23, 3000);
        };
        this.socket.onIOError = function(){
            Activity.scheduleAfter(5000, self.socket.Reconnect);
        };
        this.socket.onClose = function(){
            Activity.scheduleAfter(5000, self.socket.Reconnect);
        };
        this.Poll = function(){
            if (self.socket.connected === true) {
                self.Command.Power.GetStatus();
                System.delay(10);
                self.Command.ZoneMain.Source.GetStatus();
                System.delay(10);
                self.Command.ZoneMain.Volume.GetStatus();
                System.delay(10);
                self.Command.ZoneMain.SurroundMode.GetStatus();
                System.delay(10);
                self.Command.ZoneMain.Mute.GetStatus();
                System.delay(10);
                self.Command.RoomEQ.GetStatus();
                System.delay(10);
            }
            else {
                Activity.scheduleAfter(1000, self.Poll);
            }
        };
        this.socket.onData = function(){
            a = self.socket.read();
            var b = a.split("\r");
            for (var i = 0; i < b.length; i++) {
                switch (b[i].substr(0, 2)) {
                    case "MV":
                        if (b[i].substr(0, 3) !== "MVM") {
                            self.Command.ZoneMain.Volume.Status = self.parseVolume(b[i]);
                        }
                        break;
                    case "MS":
                        self.Command.ZoneMain.SurroundMode.Status = self.parseSurround(b[i]);
                        break;
                    case "MU":
                        self.Command.ZoneMain.Mute.Status = self.parseMute(b[i]);
                        break;
                    case "PW":
                        self.Command.Power.Status = self.parsePower(b[i]);
                        break;
                    case "SI":
                        self.Command.ZoneMain.Source.Status = self.parseInput(b[i]);
                        break;
                    case "PS":
                        self.Command.RoomEQ.Status = self.parseRoomEQ(b[i]);
                        break;
                }
            }
            self.UpdateGUI();
        };

This code needed some rewrite. Socket re-use is not recommended like this and the code is faster in object style (like: this.Action={act1:function(){self.Command("Action1");},act2:function(){self.Command("Action2");}};) .