增加待机报文缓存，无网状态也能执行待机任务；投影仪指令结果以设备状态为准

pkg/pjlink/pjlink.go

@@ -111,6 +111,7 @@ func (c *Client) sendCommand(command string) (string, error) {
 	return result, nil
 }
 
+// PowerOn 打开投影机
 func (c *Client) PowerOn() (string, error) {
 	err := c.connect()
 	if err != nil {
@@ -131,6 +132,7 @@ func (c *Client) PowerOn() (string, error) {
 	return response, nil
 }
 
+// PowerOff 关闭投影机
 func (c *Client) PowerOff() (string, error) {
 	err := c.connect()
 	if err != nil {
@@ -151,6 +153,79 @@ func (c *Client) PowerOff() (string, error) {
 	return response, nil
 }
 
+// PowerOnSync 打开投影机
+func (c *Client) PowerOnSync() (string, error) {
+	_, err := c.GetStatus()
+	if err != nil {
+		return "", err
+	}
+
+	_, _ = c.PowerOn()
+
+	// 轮询检查投影机状态，直到打开成功
+	for {
+		status, err := c.GetStatus()
+		if err != nil {
+			return "", err
+		}
+
+		if status == "1" {
+			return "投影机已打开", nil
+		} else {
+			// 如果投影机处于关闭状态，则尝试重新打开
+			_, _ = c.PowerOn()
+		}
+
+		time.Sleep(1 * time.Second)
+	}
+}
+
+// PowerOffSync 关闭投影机
+func (c *Client) PowerOffSync() (string, error) {
+	_, err := c.GetStatus()
+	if err != nil {
+		return "", err
+	}
+
+	_, _ = c.PowerOff()
+
+	// 轮询检查投影机状态，直到关闭成功
+	for {
+		status, err := c.GetStatus()
+		if err != nil {
+			return "", err
+		}
+
+		if status == "0" {
+			return "投影机已关闭", nil
+		} else {
+			// 如果投影机处于打开状态，则尝试重新关闭
+			_, _ = c.PowerOff()
+		}
+
+		time.Sleep(1 * time.Second)
+	}
+}
+
+// GetStatus 获取投影机状态
+func (c *Client) GetStatus() (string, error) {
+	err := c.connect()
+	if err != nil {
+		return "", fmt.Errorf("连接异常: %w", err)
+	}
+	defer c.close()
+
+	response, err := c.sendCommand("POWR ?")
+	if err != nil {
+		return "", err
+	}
+
+	if !strings.Contains("0123", response) {
+		return response, fmt.Errorf("unexpected response: %s", response)
+	}
+	return response, nil
+}
+
 func (c *Client) close() {
 	if c.conn != nil {
 		c.conn.Close()