Support Boolean variables

[lkm1321]

Hi,

This PR adds support for Boolean (DataType=0x0001) variables. The new features are:

1. DataType=0x0001 in EDS is parsed as C++ bool, regarding positive integer values of DefaultValue as "true"
2. It's published as ROS std_msgs/Bool object.

Addresses #268

[Roboprotos]

Hi,
Thanks for proposing this PR, this feature would be really helpful.
Since it has passed all the checks, would it be possible to have it merged with the melodic-devel branch ?

[mathias-luedtke]

This fix look okay, but I am unsure about PDO support. canopen_master does not support bit-wise access (granularity 1).
Unfortunately, I was never able to test this, because none of our devices support boolean objects.

[Roboprotos]

I see, I was mainly interested in the DCF parser, to be able to parse boolean datatype from some manufacturer specific objects that can't be mapped to PDO.

I agree PDO support should be checked before merging, or if canopen_master doesn't support granularity 1, do you think the parser could just reject files which have a mappable boolean object ?

[mathias-luedtke]

do you think the parser could just reject files which have a mappable boolean object ?

I think it should be possible to fail the init service, if a boolean gets mapped.

[lkm1321]

Hi guys, thanks for the interest. I do have a device with Boolean variables. I checked that parsing and SDOs are okay, but not PDOs. I'm happy to test whether PDO works. Would that help with having this merged?

[Roboprotos]

Hi @lkm1321, were you able to test your PR with PDOs ?

[lkm1321]

Hi @Roboprotos, I did a quick test of this feature with our device (Roboteq RGBL1896) but doesn't seem to work correctly. SDO just seems to read 0 even though the underlying value should be 1. I'm not sure if the fault is in ros_canopen or in the device's firmware, and I'd need to look at cansniffer output to debug, but I'll be away from lab until February so it'll be some time before I do any debugging. I'll update if any developments before that.