Grass Valley Performer-HD - Manual (Page 52)

3-20 Performer-HD Instruction Manual
Section 3 — Operation and Maintenance
The SMPTE standard does not say what should be returned for the Level
Configuration information field if the matrix pointer or level pointer is set
to an invalid value. Since Performer does not allow invalid values to be set,
this is not a problem.
The Level Configuration information is of limited usefulness because there
is no message for determining the allowed limits of the matrix pointer and
the level pointer. The router requires the matrix pointer to be 0 and the level
pointer to be between 0 and 2 (wildcard values are allowed too).
A single I/F Item Response message is sent containing all values (wrapped
in Begin/End) requested via Read or Update messages since the last such
response message was sent. Two separate Read messages back to back will
not produce two I/F Item Response messages containing the separate data
items, but rather will produce a single message containing them.
The Read message will result in all the values being read simultaneously,
just as with the SRDR (3F/11, Simultaneous Read Response) message.
The destinations-to-source and sources-to-destination information fields
are sensitive to whether or not the level, source, and/or destination point-
ers are set to the wildcard values (FF, FFFF). If so, reading these information
fields results in multiple I/F response values for these I/Fs; one for each
wildcard replacement combination. The SMPTE spec is a bit unclear about
how the wildcarding should apply, but this seems to be the correct way.
It is not possible to read the value of a single crosspoint, only of entire rows
or columns of the crosspoint matrix (using sources-to-destination or desti-
nations-to-source). Setting the matrix, level, and destination pointers, and
then reading the source pointer, will not give the source connected at that
matrix/level/destination. Instead, it will give the current value of the
source pointer.