VXI VT1422A - Manual (Page 255)

VT1422A Command Reference 253 Chapter 7
ALGorithm
ALGorithm:UPDate:CHANnel
ALGorithm:UPDate:CHANnel <dig_chan> This command is used to update
variables, algorithms, ALG:SCAN:RATIO, and ALG:STATE changes when the
specified digital input level changes state. When the ALG:UPD:CHAN command is
executed, the current state of the digital input specified is saved. The update will be
performed at the next update phase (UPDATE in Figure 7-1) following the channel's
change of digital state. This command is useful to synchronize multiple VT1422As
when all variable updates are to be processed at the same time.
Parameters
Comments •
The duration of the level change to the designated bit or channel MUST be at
least the length of time between scan triggers. Variable and algorithm changes
can be accepted during the INPUT or UPDATE phases (Figure 7-1) when INIT
is active. All writes to variables and algorithms occur to their buffered elements
upon receipt. However, these changes do not take effect until the ALG:UPD:CHAN
command is processed at the beginning of the UPDATE phase. Note that the
ALG:UPD:WINDow command specifies the maximum number of updates to
do. If no update command is pending when entering the UPDATE phase, then
this time is dedicated to receiving more changes from the system.
Note
As soon as the ALG:UPD:CHAN command is received, the VT1422A begins to
closely monitor the state of the update channel and cannot execute other commands
until the update channel changes state to complete the update
•
Note that an update command issued after the start of the UPDATE phase will
be buffered but not executed until the beginning of the next INPUT phase.
At that time, the current stored state of the specified digital channel is saved and
used as the basis for comparison for state change. If at the beginning of the scan
trigger the digital input state had changed, then at the beginning of the UPDATE
phase the update command would detect a change from the previous scan trigger
and the update process would begin.
•
When Accepted: Before and After INIT.
•
Send with VXIplug&play Function: hpe1422_cmd(...)
Parameter
Name
Parameter
Type
Range of
Values
Default
Units
dig_chan Algorithm
Language channel
specifier (string)
Input channel for VT1533A: Iccc.Bb
for VT1534A: Iccc
where ccc=normal channel number and
b=bit number (include ".B")
none