VXI VT1422A - Manual (Page 190)

188 Creating and Running Algorithms Chapter 6
Runtime Scan States
The Remote Signal Conditioning Units (RSCU) runtime scan can
be described as being in one of the following three states: normal,
disconnected and out of synch. In the disconnected state, the VT1422A fails
to communicate with an RSCU for various reasons (power down, no
connection, a malfunction in the cable, etc.). In the out of synch state, the
RSCU channel switching multiplexer could be out of synch with the
VT1422A due to an extra or missing trigger.
Algorithm Language
Support
Since each RSCU is connected to one of the main channels in the host
VT1422A, the operating status of each RSCU during the scanning can be
represented by the status of the corresponding main channel. A block of
memory has been reserved to hold the status for each main channel that is
connected to an RSCU. Referencing the Scan Status variable in an algorithm
will return the operating status of the specified RSCU.
The language support for status reporting is designed as follows.
Scan status variables have the syntax S1xx. S stands for Status. 1xx is the
corresponding main channel that is connected to an RSCU. Though the
possible range for main channels on a VT1422A is 00 to 63, not all of the
main channels are valid for an RSCU connection. Therefore, the current
valid range for xx is the set of discrete numbers (00, 01, 08, 09, 16, 17, 24,
25, 32, 33, 40, 41, 48, 49, 56, 57). For example, in order to read the operating
status of an RSCU connected to channel 24 of a VT1422A, S124 would be
referenced in the algorithm. S1xx is treated as an input channel and can only
be read from, not written to.
Currently, S1xx can be in one of the three states which are represented
by 0, 1, and 2.
•
S1xx is 0, when RSCU is in the normal state.
•
S1xx is 1, when RSCU is in the disconnected state.
•
S1xx is 2, when RSCU is in the out of synch state.
Operating Model
Scan Status Variables are updated just after the all channels are scanned in
the Input Phase (refer to “The Operating Sequence”). The value of the scan
status variables is available to algorithms when they execute.