Elmo Gold Maestro G-MAS, Руководство пользователя программного обеспечения, Страница: 31 / 59

G ‐ MAS – Gold Maestro Software User’s Manual Software User Manual
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// Inserting the structure parameters:
sMove_Abs_in. fAcceleration = 100000.0; // Value of the acceleration
sMove_Abs_in. fDeceleration = 100000.0; // Value of the deceleration
sMove_Abs_in. fJerk = 2000.0; // Value of the Jerk
sMove_Abs_in. eDirection = MC_POSITIVE_DIRECTION ; // MC_Direction Enumerator type
sMove_Abs_in. eBufferMode = MC_BUFFERED_MODE ; // MC_BufferMode Defines the behavior of
the axis
sMove_Abs_in. dbPosition = 100000.0; // Target position for the motion
sMove_Abs_in. fVelocity = 5000.0; // Velocity in
sMove_Abs_in. ucExecute = 1;
//
if ( MMC_MoveAbsoluteCmd (hConn, iAxisRef, &sMove_Abs_in, &sMove_Abs_out) != 0)
{
HandleError();
}
The user is responsible to create the HandleError() function. This function can optionally get
arguments, and, of ‐ course, different functions can be used at different locations of the program.
Nevertheless, the code that should perform a sequence of calls, becomes a list of if ‐ call (or call ‐ if).
This is a disadvantage of the C programming that Elmo is working to improve (see below).
Some programmers tend to bypass this difficulty using one of the following methods. We strongly
recommend not using these bypasses.
•
Call the library functions without checking the Return Code. Just ignoring it.
This will surely create a nicer and simpler code.
The assumption behind using this bypass is that the code is debugged and that there should be
no errors in the calls to the library functions. Although this is correct, there is no way to ensure
that errors will not happen in some given sequence which was not fully debugged by the user.
In the case of an error, ignoring it and continuing the program as if there was no error (the
program assumes that the function was executed properly and completely), will lead to
unexpected machine’s behavior, which can be in some cases dangerous and critical.
As stated above, Elmo strongly recommends not to use this method. Errors should be checked
and responded to, according to the suitability for the machine.
•
A second bypass is to hide the library function within a user developed wrapper function (see
above).
In this case, the wrapper function will have no return value, such as:
MyWrapperMoveAbs(..);
MyWrapperMoveAbs(..);
MyWrapperMoveAbs(..);
And the main code will indeed become simpler.
However, it is important to note that the wrapper function itself, which calls the library function,
should handle the Return Code as specified above. Handling the error within the wrapper