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Parameter Access

JCS dev_host features a parameter access subsystem for manipulating and querying device and process parameters while the system is running. Parameter transfers are asynchronous and at a lower priority than synchronous cyclic data.

Parameters are split broadly into three types: command parameters, data parameters and enumerated parameters.

Command parameters

Command parameters are parameters that take no data. Issuing a command parameter will trigger some action.

For example dev_motor_controller command controller_stop will cause the controller to stop. It takes no other data.

Data parameters

Data parameters are used to read or write data into device or process parameters. Data parameters take in single values or std::vectors.

Enumerated parameters

Enumerated parameters are used to transfer discrete setting to devices or processes. Available enumerated values are described in the device or processes software reference.

Parameter access notes

  • Parameter access functions are blocking; do not access the parameter functions from within the real-time loop.
  • Parameter access functions time-out after 500ms.
  • Parameter access functions are currently only available for use from a single thread.