Rosserial and Arduino resets

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For anyone else having this issue, we found a workaround. When the device was unplugged from the USB port, we'd need to reprogram it or change the baud rate a couple times. I noticed the devices worked fine when using minicom and other serial programs, so we looked at the source of these programs to see what they're doing. minicom "resets" the modem by setting the baud to 0 and back. We just made SerialClient.py do the same:

self.port = Serial(port, baud, timeout=self.timeout*0.5)

changes to

self.port = Serial(port, 0, timeout=self.timeout*0.5)
self.port.baudrate = baud
time.sleep(2.0) # give usb chip time to reset

Bence, thanks for the link but that did not work. I am a colleague of Parker's and have been working with him on this issue. Upon further research we have found that the problem only occurs if the serial cable is disconnected after using serial_node.py to communicate with the node. In other words we can flash the Arduino with the Hello World sketch, disconnect and reconnect the USB cable and communicate with the node via serial_node.py. However if we disconnect the USB cable after doing so, regardless of whether the Arduino is powered via the barrel plug, we are no longer able to communicate with the node via serial_node.py upon reconnecting the serial cable.

Even more strange I just tried this at home and the results are completely different. In fact everything works as expected. I flash the Arduino and communicate with it via serial_node.py. I then disconnect the USB cable, reconnect it and communicate with it via serial_node.py again. No problem. I can repeat this process as much I as I like and all works well.

In both cases our machines are running Ubuntu 11.10, ROS electric and are completely up-to-date with respect to software updates. Spot checking the ros-electric packages shows they are the same version on both machines. It's fine that it works at home but we need it to work in the lab as well. Any thoughts as to how to correct this issue would be greatly appreciated.

Your problem might be related to this issue (although the error message is slightly different): https://github.com/ros-drivers/rosser...

I am encountering this problem with ubuntu 14.04 and different kernel versions (3.10.96, 3.13.0, 3.16.0).

I found three possible workarounds:

• Use the current xenial kernel (version 4.4.0) with ubuntu 14.04 (DISCLAIMER: This is a serious change in your system and might cause trouble such as driver incompatibilities)
• Start the serial_node with baud rate 0, exit and restart the serial node with the correct baud rate. You have to repeat this every time the error occurs.
• Modify SerialClient.py according to the suggestion of kvogt

I tried kvogt solution without success, but found that these other lines worked for me:

self.port = Serial(port, 0, timeout=self.timeout*0.5)
self.port.baudrate = 1200
time.sleep(1.0)
self.port.baudrate = baud
time.sleep(1.0)

Well i got this type of problem too, and after some time, i have already tryed all those hacks and nothing worked.

I think this problem is caused by some type of problem with arduinos which use bad usb_serial converter chips. The solution that i worked out is puting those lines in the beginning of the client.py:

        self.port = Serial()
        self.port.port = self.portAdress
        self.port.baudrate = self.baudrate
        self.port.timeout = self.timeout
        self.port.dsrdtr = False
        self.port.open()
        self.port.setParity(PARITY_NONE)
        self.port.setParity(PARITY_ODD)
        self.port.setParity(PARITY_NONE)
        #with the port open reset the arduino
        self.port.setDTR(True)
        time.sleep(0.5)
        self.port.flushInput()
        self.port.setDTR(False)
        time.sleep(0.5)

I dont know why, but the parity change did the trick, dont remove it..