Unable to subscribe and plot to my custom LCM Message

[zulfiqar-zaidi]

I am trying to use lcm-signal-scope to plot values from my custom LCM message. My LCM message has the following definition:

`struct my_message {
// The timestamp in microseconds.
int64_t utime;

// position
float q[23];

// velocity
float v[22];
}`

The name of the channel is "MY_MESSAGE". I wrote the following python script to plot the signal:

addSignal('MY_MESSAGE', msg.utime, msg.q[0])

I used the following command to run the signal scope:

$ build/bin/signal-scope examples/example9.py

I get the following error:
File "<string>", line 143, in decodeMessageFunction
KeyError: 'R\xff\xd3\tO\x1a\x9b\x1f'

Any suggestions to overcome this issue will be highly appreciated.

[patmarion]

That error indicates that signal-scope wasn't able to determine the message type. Sorry, that error message isn't very helpful.

When signal-scope starts it will search for lcm messages types and print information about all the types that it finds. You'll see information printed in the terminal that looks like:

Loaded <count> lcm message types from: <package name>

You have to make sure:

1. you compiled your message types for python
2. the message type python module is installed in a standard location or somewhere in your PYTHONPATH