previously received data remains

[a-higuchi]

Description

If the DLC(Data Length Code) is less than 8, the previously received data remains in the "data" field of the topic sent by ros2_socketcan.

When supporting multiple types of HW with the same CAN-ID but different DLCs, unintended behavior may occur if garbage is included in the reception result of can_receiver.

I checked with the following steps.

Preparation

• Install can-utils

sudo apt install can-utils

• Enable vcan

sudo modprobe vcan
sudo ip link add dev vcan0 type vcan
sudo ip link set up vcan0

• Invoke ros2_socketcan

ros2 launch ros2_socketcan socket_can_bridge.launch.xml interface:=vcan0

• Invoke candump

candump vcan0

• Topic monitoring

ros2 topic echo /from_can_bus

Procedure

Send the following CAN data with cansend.

cansend vcan0 200#1122334455667788
cansend vcan0 123#aa

Output

• candump output

  vcan0  200   [8]  11 22 33 44 55 66 77 88
  vcan0  123   [1]  AA

• Topic output

header:
  stamp:
    sec: 1661924425
    nanosec: 956480272
  frame_id: can
id: 512
is_rtr: false
is_extended: false
is_error: false
dlc: 8
data:
- 17
- 34
- 51
- 68
- 85
- 102
- 119
- 136
---
header:
  stamp:
    sec: 1661924437
    nanosec: 538097128
  frame_id: can
id: 291
is_rtr: false
is_extended: false
is_error: false
dlc: 1
data:
- 170
- 34
- 51
- 68
- 85
- 102
- 119
- 136
---

[JWhitleyWork]

Closed by #18.