# Is it possible to command the robot using another script when running stretch\_web\_interface **URL:** \ **Category:** Ask\ **Created:** [August 4, 2022, 4:20pm UTC](https://forum.hello-robot.com/t/is-it-possible-to-command-the-robot-using-another-script-when-running-stretch-web-interface/448 "2022-08-04T16:20:18Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Bread\_wq](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.hello-robot.com/bread_wq/32/278_2.png) [@Bread\_wq](https://forum.hello-robot.com/u/Bread_wq)\ **Post date:** [August 4, 2022, 4:20pm UTC](https://forum.hello-robot.com/t/is-it-possible-to-command-the-robot-using-another-script-when-running-stretch-web-interface/448/1 "2022-08-04T16:20:18Z")
Hi Stretch Community! I want to run a python script which sends commands to the robot while the web interface is running. The main purpose of running the two scripts at the same time is to get the camera feed from the web\_interface. Here is the error I got: ```auto [ERROR] [pimu]: Port /dev/hello-pimu is busy. Check if another Stretch Body process is already running [WARNING] [pimu]: Unable to open serial port for device /dev/hello-pimu [ERROR] [hello-motor-left-wheel]: SerialException(5): could not open port /dev/hello-motor-left-wheel: [Errno 5] Input/output error: '/dev/hello-motor-left-wheel' [WARNING] [hello-motor-left-wheel]: Unable to open serial port for device /dev/hello-motor-left-wheel [ERROR] [hello-motor-right-wheel]: Port /dev/hello-motor-right-wheel is busy. Check if another Stretch Body process is already running [WARNING] [hello-motor-right-wheel]: Unable to open serial port for device /dev/hello-motor-right-wheel [ERROR] [hello-motor-lift]: Port /dev/hello-motor-lift is busy. Check if another Stretch Body process is already running [WARNING] [hello-motor-lift]: Unable to open serial port for device /dev/hello-motor-lift [ERROR] [hello-motor-arm]: Port /dev/hello-motor-arm is busy. Check if another Stretch Body process is already running [WARNING] [hello-motor-arm]: Unable to open serial port for device /dev/hello-motor-arm [ERROR] [wacc]: Port /dev/hello-wacc is busy. Check if another Stretch Body process is already running [WARNING] [wacc]: Unable to open serial port for device /dev/hello-wacc Traceback (most recent call last): File "[BluetoothAP.py](http://bluetoothap.py/)", line 23, in robot.startup() File "/home/zackory/.local/lib/python2.7/site-packages/stretch_body/robot.py", line 159, in startup if not self.devices[k].startup(threaded=False): File "/home/zackory/.local/lib/python2.7/site-packages/stretch_body/head.py", line 21, in startup return DynamixelXChain.startup(self, threaded=threaded) File "/home/zackory/.local/lib/python2.7/site-packages/stretch_body/dynamixel_X_chain.py", line 81, in startup if not self.motors[mk].startup(threaded=False): File "/home/zackory/.local/lib/python2.7/site-packages/stretch_body/dynamixel_hello_XL430.py", line 160, in startup self.motor.set_return_delay_time(self.params['return_delay_time']) File "/home/zackory/.local/lib/python2.7/site-packages/stretch_body/dynamixel_XL430.py", line 404, in set_return_delay_time dxl_comm_result, dxl_error = self.packet_handler.write1ByteTxRx(self.port_handler, self.dxl_id,XL430_ADDR_RETURN_DELAY_TIME, int(x)) File "/opt/ros/melodic/lib/python2.7/dist-packages/dynamixel_sdk/protocol2_packet_handler.py", line 653, in write1ByteTxRx return self.writeTxRx(port, dxl_id, address, 1, data_write) File "/opt/ros/melodic/lib/python2.7/dist-packages/dynamixel_sdk/protocol2_packet_handler.py", line 643, in writeTxRx rxpacket, result, error = self.txRxPacket(port, txpacket) File "/opt/ros/melodic/lib/python2.7/dist-packages/dynamixel_sdk/protocol2_packet_handler.py", line 346, in txRxPacket rxpacket, result = self.rxPacket(port) File "/opt/ros/melodic/lib/python2.7/dist-packages/dynamixel_sdk/protocol2_packet_handler.py", line 257, in rxPacket rxpacket.extend(port.readPort(wait_length - rx_length)) File "/opt/ros/melodic/lib/python2.7/dist-packages/dynamixel_sdk/port_handler.py", line 80, in readPort return [ord(ch) for ch in self.ser.read(length)] File "/home/zackory/.local/lib/python2.7/site-packages/serial/serialposix.py", line 596, in read 'device reports readiness to read but returned no data ' serial.serialutil.SerialException: device reports readiness to read but returned no data (device disconnected or multiple access on port?) ``` Is there a way to fix this? Or are there any python codes I can use to get the real time video feed from the robot? Thank you so much for your help! ---
**Author:** ![bshah](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.hello-robot.com/bshah/32/55_2.png) [@bshah](https://forum.hello-robot.com/u/bshah)\ **Post date:** [August 5, 2022, 7:44am UTC](https://forum.hello-robot.com/t/is-it-possible-to-command-the-robot-using-another-script-when-running-stretch-web-interface/448/2 "2022-08-05T07:44:43Z")
Hi @Bread_wq, only one program can access the hardware at the same time and from the errors you’re seeing, it seems like the second script is attempting to access the hardware when it calls `robot.startup()`. While the web interface is running, the ROS Realsense driver is running as well. If you’d like to access the camera feed while the web interface is running, you can write another ROS node that subscribes to the Realsense topics. Here’s a [tutorial](https://github.com/hello-robot/stretch_tutorials/blob/main/perception.md) (and an [additional example](https://github.com/hello-robot/stretch_tutorials/blob/main/example_7.md)) on the subject of using the Realsense topics. Let me know if you have any questions. Happy to suggest changes if you link your second script here. ---
**Author:** ![hello-garv](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.hello-robot.com/hello-garv/32/296_2.png) [@hello-garv](https://forum.hello-robot.com/u/hello-garv)\ **Post date:** [August 8, 2022, 10:35pm UTC](https://forum.hello-robot.com/t/is-it-possible-to-command-the-robot-using-another-script-when-running-stretch-web-interface/448/3 "2022-08-08T22:35:05Z")
Hello, I believe Binit’s tips might be the more efficient solution for you in this case, but I have been working with the interface quite a bit this summer and wanted to chime in with a couple things I have learned. Here is what has been working well for me as I write separate nodes to work alongside the interface: - To move the base, I publish twist messages directly to the /stretch/cmd\_vel topic (works well for simple translations and rotations, but I would not try anything much more complicated) - For full body joint control, I use the send\_command function from the [keyboard teleop node](https://github.com/hello-robot/stretch_ros/blob/master/stretch_core/nodes/keyboard_teleop). The key to avoiding conflicts is to add two services calls. Before using the single joint control in the send\_command function, you must call the ‘/switch\_to\_position\_mode’ service. After the single joint command is sent, in order to be able to control the robot from the interface again, you must reset the mode by calling the ‘/switch\_to\_navigation\_mode’ service. I will add a disclaimer that I am working with the University of Washington’s Human-Centered Robotics Lab’s fork of the interface, which has gone through some significant changes so it is possible these tips will not apply. If you would like an example of these ideas, you can check out a [node I wrote](https://github.com/hcrlab/stretch_web_interface/blob/anna/nodes/save_pose) to save positions relative to ArUco tags in my development branch. I hope this is helpful, please feel free to reach out to me with any questions! ---
**Author:** ![Bread\_wq](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.hello-robot.com/bread_wq/32/278_2.png) [@Bread\_wq](https://forum.hello-robot.com/u/Bread_wq)\ **Post date:** [August 8, 2022, 11:10pm UTC](https://forum.hello-robot.com/t/is-it-possible-to-command-the-robot-using-another-script-when-running-stretch-web-interface/448/4 "2022-08-08T23:10:22Z")
Hi Binit! I think your advice is really helpful. ROS is the way to go, and I found this [How to get RGB Depth stream in python ROS · Issue #1514 · IntelRealSense/realsense-ros · GitHub](https://github.com/IntelRealSense/realsense-ros/issues/1514) really helpful combined with your suggestion! If anyone is interested, just modify the line ` rospy.Subscriber('/camera/aligned_depth_to_color/image_raw', Image, callback)` into ` rospy.Subscriber('/camera/color/image_raw', Image, callback)` And you can access the video stream without causing conflicts with other programs controlling the robot! ---
**Author:** ![bshah](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.hello-robot.com/bshah/32/55_2.png) [@bshah](https://forum.hello-robot.com/u/bshah)\ **Post date:** [August 10, 2022, 4:21pm UTC](https://forum.hello-robot.com/t/is-it-possible-to-command-the-robot-using-another-script-when-running-stretch-web-interface/448/5 "2022-08-10T16:21:17Z")
Glad to hear it @Bread_wq!