Technical data

Programming
CPU 317T: Technology Functions
5-10 A5E00251798-03
Commands without defined termination
These commands can not report completion and thus do not have an output
parameter Done. Instead, they return a status message to indicate the first time the
required operating state has been reached. If the axis is to be accelerated to a
certain velocity, for example, the output parameter InVelocity (FB
MC_MoveVelocity) is set to indicate the first time this velocity has been reached.
The command continues to be processed, and the FB outputs will be updated until
the command is overridden or if an error occurs. The status of the technology
function then changes and CommandAborted is set TRUE.
Overriding commands with the same FB
The application may require the override of a busy command with a command of
the same type, e.g. positioning to 200 overrides positioning to 100. In this case,
use a FB that has a different instance DB compared to the command you want to
override. Otherwise, the busy ("old") command can no longer be monitored at the
FB outputs. This may present a problem, in particular if the start of the new
command is prevented as a result of error.
Each one of the instance DBs has its own input buffer. If commands with the same
instance DB follow in rapid succession, a consistency problem may develop in the
input buffer. New commands are thus rejected with error (0x804C) as long as the
input buffer is busy. In this case, it is also no longer possible to monitor the
command based on the FB outputs.