# Consecutive commands in depth hold mode **URL:** \ **Category:** Blue Robotics Software\ **Created:** [March 3, 2018, 10:15am UTC](https://discuss.bluerobotics.com/t/consecutive-commands-in-depth-hold-mode/2257 "2018-03-03T10:15:20Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![vatsal\_shah](https://avatars.discourse-cdn.com/v4/letter/v/0ea827/32.png) [@vatsal\_shah](https://discuss.bluerobotics.com/u/vatsal_shah)\ **Post date:** [March 3, 2018, 10:15am UTC](https://discuss.bluerobotics.com/t/consecutive-commands-in-depth-hold-mode/2257/1 "2018-03-03T10:15:20Z")
We are using depth hold mode while testing using a wifi connection. ```auto import time from pymavlink import mavutil mavutil.set_dialect("ardupilotmega") autopilot = mavutil.mavlink_connection('/dev/ttyACM0') msg = None # wait for autopilot connection while msg is None: msg = autopilot.recv_msg() #print msg # The values of these heartbeat fields is not really important here # I just used the same numbers that QGC uses # It is standard practice for any system communicating via mavlink emit the HEARTBEAT message at 1Hz! Your autopilot may not behave the way you want otherwise! autopilot.mav.heartbeat_send( 6, # type 8, # autopilot 192, # base_mode 0, # custom_mode 4, # system_status 3 # mavlink_version ) autopilot.mav.command_long_send( 1, # autopilot system id 1, # autopilot component id 400, # command id, ARM/DISARM 0, # confirmation 1, # arm! 0,0,0,0,0,0 # unused parameters for this command ) print 'this is arm' autopilot.mav.manual_control_send(1, 0, 0, -50, 0, 0) print 'this is down' time.sleep(2) #autopilot.set_mode(2) #print 'Alt HOld' autopilot.mav.command_long_send(1,1,176,0,2,0,0,0,0,0,0) print 'Alt HOld' time.sleep(2) autopilot.mav.command_long_send( 1, # autopilot system id 1, # autopilot component id 400, # command id, ARM/DISARM 0, # confirmation 0, # disarm! 0,0,0,0,0,0 # unused parameters for this command ) print 'disarm' #time.sleep(1) autopilot.mav.command_long_send( 1, # autopilot system id 1, # autopilot component id 400, # command id, ARM/DISARM 0, # confirmation 1, # arm! 0,0,0,0,0,0 # unused parameters for this command ) print 'this is arm 2' t=8 while(t): autopilot.mav.manual_control_send(1, 2000, 0, 500, 0, 0) print 'this is forward' time.sleep(2) t=t-1 autopilot.mav.manual_control_send(1, 0, 1500, 500, 0, 0) print 'sway' autopilot.mav.command_long_send( 1, # autopilot system id 1, # autopilot component id 400, # command id, ARM/DISARM 0, # confirmation 0, # disarm! 0,0,0,0,0,0 # unused parameters for this command ) print 'disarm' ``` the bot performs the depth hold mode and after giving a command the bot performs the command and gets disarmed We cannot use more than one command after going into depth hold. please revert as soon as possible ---
**Author:** ![patrickelectric](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/patrickelectric/32/2162_2.png) [@patrickelectric](https://discuss.bluerobotics.com/u/patrickelectric)\ **Post date:** [March 3, 2018, 10:28am UTC](https://discuss.bluerobotics.com/t/consecutive-commands-in-depth-hold-mode/2257/2 "2018-03-03T10:28:47Z")
@vatsal_shah, We have some examples of how to use pymavlink with the ROV, please, take a look [here](https://www.ardusub.com/developers/pymavlink.html). About your code, you need to connect via UDP to mavproxy, take a look in our [software components](https://www.ardusub.com/software/components.html) to see how the mavlink communication is handle. ---
**Author:** ![jwalser](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/jwalser/32/2234_2.png) [@jwalser](https://discuss.bluerobotics.com/u/jwalser)\ **Post date:** [March 3, 2018, 4:32pm UTC](https://discuss.bluerobotics.com/t/consecutive-commands-in-depth-hold-mode/2257/3 "2018-03-03T16:32:35Z")
You need to send the HEARTBEAT message to the autopilot at 1Hz. This is a safety mechanism. ---
**Author:** ![vatsal\_shah](https://avatars.discourse-cdn.com/v4/letter/v/0ea827/32.png) [@vatsal\_shah](https://discuss.bluerobotics.com/u/vatsal_shah)\ **Post date:** [March 3, 2018, 5:22pm UTC](https://discuss.bluerobotics.com/t/consecutive-commands-in-depth-hold-mode/2257/4 "2018-03-03T17:22:08Z")
How do we send the heartbeat continuously at 1Hz through python script? so at the end, the above code works as intended. Please help. It’s urgent. ---
**Author:** ![jwalser](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/jwalser/32/2234_2.png) [@jwalser](https://discuss.bluerobotics.com/u/jwalser)\ **Post date:** [March 3, 2018, 5:32pm UTC](https://discuss.bluerobotics.com/t/consecutive-commands-in-depth-hold-mode/2257/5 "2018-03-03T17:32:12Z")
```auto while(True): send_heartbeat(): time.sleep(1) ``` Or if you want to do other things: ```auto lastHeartbeat_t = 0 while(True) t = time.time() if (t > lastHeartbeat_t + 1): send_heartbeat lastHeartbeat_t = t ...do other things... ``` ---
**Author:** ![vatsal\_shah](https://avatars.discourse-cdn.com/v4/letter/v/0ea827/32.png) [@vatsal\_shah](https://discuss.bluerobotics.com/u/vatsal_shah)\ **Post date:** [March 3, 2018, 5:46pm UTC](https://discuss.bluerobotics.com/t/consecutive-commands-in-depth-hold-mode/2257/6 "2018-03-03T17:46:17Z")
Thanks a lot. And one more thing. using the below python script, connection.mav.manual\_control\_send(1,1000,0,0,0,0,0) #forward 1000 how to run only the front motors? We do not want the back thrusters to rotate. ---
**Author:** ![jwalser](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/jwalser/32/2234_2.png) [@jwalser](https://discuss.bluerobotics.com/u/jwalser)\ **Post date:** [March 3, 2018, 5:51pm UTC](https://discuss.bluerobotics.com/t/consecutive-commands-in-depth-hold-mode/2257/7 "2018-03-03T17:51:51Z")
This is not possible, why do you want to do this? ---
**Author:** ![vatsal\_shah](https://avatars.discourse-cdn.com/v4/letter/v/0ea827/32.png) [@vatsal\_shah](https://discuss.bluerobotics.com/u/vatsal_shah)\ **Post date:** [March 3, 2018, 6:00pm UTC](https://discuss.bluerobotics.com/t/consecutive-commands-in-depth-hold-mode/2257/8 "2018-03-03T18:00:51Z")
Because one of our rear thruster’s has issues. It does not rotate at the same speed as others. And so the bot travels in a curved trajectory. And we do not have time to get the replacement. So please help. ---
**Author:** ![jwalser](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/jwalser/32/2234_2.png) [@jwalser](https://discuss.bluerobotics.com/u/jwalser)\ **Post date:** [March 3, 2018, 6:07pm UTC](https://discuss.bluerobotics.com/t/consecutive-commands-in-depth-hold-mode/2257/9 "2018-03-03T18:07:40Z")
Unplug the two motors that you do not want to spin.