Error on um6_driver when trying to change update_rate from Heron (clearpathrobotics)

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Hello, I am trying to change the update rate of UM6 on the HERON and got error when update rate is higher than 40(Hz).

Detailed description:

The um6 package is exactly same from: https://github.com/ros-drivers/um6.git

The default update_rate of um6_driver is 20(Hz), specified in the um6/src/main.cpp as a parameter update_rate. There ‘s error when changing update_rate to any number higher than 40(Hz).

How to duplicate:

Try turning on debug output for the node, which may give more clues as to what's gone wrong. Add the last line to /opt/ros/kinetic/share/ros/config/rosconsole.config:

#
#   rosconsole will find this file by default at $ROS_ROOT/config/rosconsole.co$
#
#   You can define your own by e.g. copying this file and setting
#   ROSCONSOLE_CONFIG_FILE (in your environment) to point to the new file
#
log4j.logger.ros=INFO
log4j.logger.ros.roscpp.superdebug=WARN
log4j.logger.ros.um6=DEBUG

Then, set the update_rate of um6_driver to 50(Hz):

    $ rosrun um6 um6_driver _update_rate:=50
[ INFO] [1566411650.479349448]: Successfully connected to serial port.
[ INFO] [1566411650.487981538]: Setting update rate to 50Hz
[DEBUG] [1566411650.488606598]: Computed checksum on string of length 9 as 2803.
[DEBUG] [1566411650.488815348]: Generated message 00 of overall length 11.
[DEBUG] [1566411650.512419927]: Received packet 5e with batched (2) data.
[DEBUG] [1566411650.512712327]: Received packet 6a with batched (4) data.
[DEBUG] [1566411650.512910947]: Received packet 6e with batched (4) data.
[DEBUG] [1566411650.513085337]: Received packet 72 with batched (4) data.
[DEBUG] [1566411650.513290858]: Received packet 76 with non-batched data.
[DEBUG] [1566411650.562617821]: Received packet 76 with non-batched data.
[ WARN] [1566411650.566446769]: Discarding packet due to bad checksum.
[DEBUG] [1566411650.566751834]: Serial read timed out waiting for ack. Attempting to retransmit.
[DEBUG] [1566411650.566962844]: Computed checksum on string of length 9 as 2803.
[DEBUG] [1566411650.567081779]: Generated message 00 of overall length 11.
[ WARN] [1566411650.567452129]: Serial read buffer is 490, now flushing in an attempt to catch up.
[ WARN] [1566411650.619233649]: Discarded 9 junk byte(s) preceeding packet.
[DEBUG] [1566411650.619504600]: Received packet 72 with batched (4) data.
[ WARN] [1566411650.619695895]: Serial read buffer is 469, now flushing in an attempt to catch up.
[ WARN] [1566411650.676300178]: Discarded 25 junk byte(s) preceeding packet.
[DEBUG] [1566411650.676707183]: Received packet 6e with batched (4) data.
[ WARN] [1566411650.677062018]: Serial read buffer is 453, now flushing in an attempt to catch up.
[ WARN] [1566411650.734512847]: Discarded 17 junk byte(s) preceeding packet.
[DEBUG] [1566411650.735037627]: Received packet 66 with batched (4) data.
[ WARN] [1566411650.735379642]: Serial read buffer is 461, now flushing in an attempt to catch up.
[ WARN] [1566411650.789343914]: Discarded 10 junk byte(s) preceeding packet.
[DEBUG] [1566411650.789549579]: Received packet 60 with batched (2) data.
[ WARN] [1566411650.789739199]: Serial read buffer is 476, now flushing in an attempt to catch up.
[ WARN] [1566411650.845231651]: Discarded 7 junk byte(s) preceeding packet.
[DEBUG] [1566411650.845415282]: Received packet 76 with non-batched data.
[ WARN] [1566411650.845612497]: Serial read buffer is 483, now flushing ...