diff --git a/cmd/start.go b/cmd/start.go
index 5c610e6..197f196 100644
--- a/cmd/start.go
+++ b/cmd/start.go
@@ -36,7 +36,9 @@ and usage of using your command. For example:
 Cobra is a CLI library for Go that empowers applications.
 This application is a tool to generate the needed files
 to quickly create a Cobra application.`,
-	Run: start,
+	Run: func(cmd *cobra.Command, args []string) {
+		start()
+	},
 }
 
 var run bool
@@ -55,7 +57,7 @@ func init() {
 	// startCmd.Flags().BoolP("toggle", "t", false, "Help message for toggle")
 }
 
-func start(cmd *cobra.Command, args []string) {
+func start() {
 	// Go signal notification works by sending `os.Signal`
 	// values on a channel. We'll create a channel to
 	// receive these notifications (we'll also make one to
diff --git a/cmd/test.go b/cmd/test.go
index 754a9a1..18c2391 100644
--- a/cmd/test.go
+++ b/cmd/test.go
@@ -28,10 +28,12 @@ var testCmd = &cobra.Command{
 	Long: `loading config file
 Test serial port
 Test load sqlite database and init table`,
-	Run: test,
+	Run: func(cmd *cobra.Command, args []string) {
+		test()
+	},
 }
 
-func test(cmd *cobra.Command, args []string) {
+func test() {
 	log.Println("Testing environment")
 	_ = utils.OpenPort(device, baudrate, bytesize)
 
diff --git a/utils/serial.go b/utils/serial.go
index 8c8feb1..9c3665c 100644
--- a/utils/serial.go
+++ b/utils/serial.go
@@ -31,6 +31,9 @@ func OpenPort(device string, baudrate int, bytesize byte) error {
 
 func ReadPort() ([]byte, int){
 	buffer := make([]byte, 256)
+	if !ServerRunning {
+		return buffer, 0
+	}
 	count,err := port.Read(buffer)
 	if err != nil && err != io.EOF {
 		log.Println("error in read port ", err)