document stop1/modbus launch files

[JonathanGruner]

Commit

Version 0.5.7

Steps to reproduce

1. Open launch files inside prbt_hardware_support
2. Try to understand the parameters / arguments
3. Search comments--->There you will find the issue...no comments.
4. You won't be able to understand the code

Expected behavior

Well documented files, especally launch files, config files, etc.

Observed behavior

missing comments / references.

[ct2034]

@JonathanGruner Thanks for your feedback. Unfortunately, this is a relatively broad topic. Could you please give an example of where you think we lack documentation. Also, feel free to open a pull request!

[jschleicher]

This concerns e.g. launch files in the folder

https://github.com/PilzDE/pilz_robots/blob/4d49235f22a0816058a40117aeb5f22b850d31f1/prbt_hardware_support/launch/stop1_executor_node.launch#L18-L20

Sometimes a reference to the main readme would be enough, but in this case the readme doesn't mention stop1_executor_node at all.

[JonathanGruner]

Another great exampel would be: https://github.com/PilzDE/pilz_robots/blob/4d49235f22a0816058a40117aeb5f22b850d31f1/prbt_hardware_support/launch/modbus_client.launch#L29-L40

I don't want to bother you with a detailed description of each command/parameter, but if you could briefly explain what you are doing I would be happy :)

For example: num_first_register_to_read: First register adress of 4x registers type in modicon notation num_registers: first = runpermitted, second = baketest, third = sth other

[JonathanGruner]

https://github.com/PilzDE/pilz_robots/blob/24a1c5dd8ad6be342b27bfef5a3bb13b471003ef/prbt_hardware_support/config/modbus_read_api_spec_pss4000.yaml#L1-L4

Here you could write an comment, that users are able to add different Registers

[JonathanGruner]

Closed regarding to closed issue #309 (Modbus specification) and #250 (Missing Modbus information)