Timeout

[neochaos42]

Hello I am running both nodes on a single machine and serial_motor_demo keeps timing out. Error: Serial Timeout on command: e
This keeps printing.
The system works using miniterm but not using these nodes.

[neochaos42]

ros2 run serial_motor_demo driver --ros-args -p encoder_cpr:=1796 -p loop_rate:=30 -p serial_port:=/dev/ttyUSB0 -p baud_rate:=57600
Connecting to port /dev/ttyUSB0 at 57600.
Connected to Serial<id=0xffffb4471c40, open=True>(port='/dev/ttyUSB0', baudrate=57600, bytesize=8, parity='N', stopbits=1, timeout=1.0, xonxoff=False, rtscts=False, dsrdtr=False)
Error: Serial timeout on command: e
Error: Serial timeout on command: e
Error: Serial timeout on command: e
Error: Serial timeout on command: e

[joshnewans]

As I was testing this today for the humble upgrade, I realised that I had always sort of had problems like this, except usually just on the first connection and after that it was fine. I.e. it would print only once.

I wonder if this is related or not...

[virensompura]

@neochaos42 same issue

[ryanmaxwell96]

Same issue. Mine prints 3 times. The gui reads: "Encoders: XXX XXX Speed rev/s: XXX XXX" and the motors do not spin. However I can listen to the topic from my dev machine and see that the messages are being successfully published. The rpi is just not listening to it.

On the raspberry pi:

rpi@rpi:~/robot_ws$ ros2 run serial_motor_demo driver --ros-args -p serial_port:=/dev/ttyUSB0 -p baud_rate:=57600 -p loop_rate:=30 -p encoder_cpr:=2500
Connecting to port /dev/ttyUSB0 at 57600.
Connected to Serial<id=0xffff9cc68700, open=True>(port='/dev/ttyUSB0', baudrate=57600, bytesize=8, parity='N', stopbits=1, timeout=1.0, xonxoff=False, rtscts=False, dsrdtr=False)
Error: Serial timeout on command: e
Error: Serial timeout on command: e
Error: Serial timeout on command: e

On the development machine after running, "ros2 run serial_motor_demo gui" and "ros2 topic echo /motor_command" in a separate terminal after 3 different publishes:
is_pwm: true
mot_1_req_rad_sec: 57.0
mot_2_req_rad_sec: 47.0

is_pwm: true
mot_1_req_rad_sec: -133.0
mot_2_req_rad_sec: -140.0

is_pwm: true
mot_1_req_rad_sec: 128.0
mot_2_req_rad_sec: -140.0

[ryanmaxwell96]

Update: The XXX XXX clued me in that ROS2 communication was not working so I used the talker/listener program to test this. Sure enough, ROS was not communicating over my network. This ended up being firewall issues which were overcome by

1. Putting ROS_DOMAIN_ID=0 in to the .bashrc on each machine
2. Entering "sudo ufw allow in proto udp to/from " on both machines, both for "to" and "from"
3. Actually running "ros2 run demo_nodes_cpp talker/listener" on both machines rather than just using "ros2 topic list" to make sure the machine could see the other's published topics. When I first just ran the talker and then ros2 topic list, nothing showed up so I think it takes some time for the ros node to appear.

So now it is working!

[huubeikens]

Same issue. The ROS2 communication works fine but still get serial timeouts:

ros2 run serial_motor_demo driver --ros-args -p encoder_cpr:=3440 -p loop_rate:=30 -p serial_port:=/dev/ttyACM0 -p baud_rate:=57600
Connecting to port /dev/ttyACM0 at 57600.
Connected to Serial<id=0xffff8e370cd0, open=True>(port='/dev/ttyACM0', baudrate=57600, bytesize=8, parity='N', stopbits=1, timeout=1.0, xonxoff=False, rtscts=False, dsrdtr=False)
Error: Serial timeout on command: e
rror: Serial timeout on command: e
Error: Serial timeout on command: e
Error: Serial timeout on command: m 573 573
Error: Serial timeout on command: e
Error: Serial timeout on command: e

If I open a python3 terminal and past the following code snipit from driver.py, I get a valid response:

import serial

ser = serial.Serial('/dev/ttyACM0', 57600, timeout=1.0)  # open serial port

cmd_string= "e"
cmd_string += "\r"
ser.write(cmd_string.encode("utf-8"))
print("Sent: " + cmd_string)

c = ''
value = ''
while c != '\r':
    c = ser.read(1).decode("utf-8")
    if (c == ''):
        print("Error: Serial timeout on command ")
        break
    value += c

print(value)

Anyone has an idea how to debug this further?

[huubeikens]

Solved it! Add a 2 second sleep after creating the Serial object:

        print(f"Connecting to port {self.serial_port} at {self.baud_rate}.")
        self.conn = serial.Serial(self.serial_port, self.baud_rate, timeout=1.0)
        time.sleep(2)

Issue (and solution) that's causing it is described here