Secondary Program Limitations

Secondary programs are typically run as support programs, they are designed to be executed concurrently with the primary program using real time control loop. Entire execution time is added to single real time cycle. Due to their nature they have some limitations in using specific commands.

Motion Commands: Using any motion commands in secondary program such as movej, movel and servoj will not work. They will cause an error of "Runtime is too much behind". The motion commands depend on the external factor (real robot motion) and are waiting for the result of the execution, which is not possible in secondary programs.

Interpreter Mode: Sending new commands during runtime essentially goes against the design of secondary programs. This will again give you the error of runtime too much behind.

Socket: Socket communication can be used within secondary programs, but this is limited to executing simple non-blocking commands like single socket_send. Slow remote server or attempt to execute multiple socket commands will cause "Runtime too much behind", or prevent controller from executing real-time tasks. Socket commands should be avoided in secondary programs.

XMLRPC: Like socket, XMLRPC calls can be used in secondary programs although they need to be executed very quickly by remote server. XMLRPC calls should be avoided in secondary programs.

Sleep: Sleep, similar to motion commands is a blocking call by nature. It requires multiple real-time cycles to complete. Using Sleep will cause an error of "Runtime is too much behind"

Threads: Threads in secondary programs are not supported. Thread code execution is not guaranteed, and leads to undefined behaviour.