VXI VT1422A - Manual (Page 256)

254 VT1422A Command Reference Chapter 7
ALGorithm
Command
Sequence
The following example shows three scalars being written with the associated update
command following. When the ALG:UPD:CHAN command is received, it will read
the current state of channel 108, bit 0. At the beginning of the UPDATE phase, a
check will be made to determine if the stored state of channel 108 bit 0, is different
from the current state. If so, the update of all three scalars take effect next Phase 2.
INIT
ALG:SCAL 'ALG1','Setpoint',25
ALG:SCAL 'ALG1','P_factor',1.3
ALG:SCAL 'ALG2','P_factor',1.7
ALG:UPD:CHAN 'I108.B0'
update on state change at bit zero of 8-bit
channel 8
ALGorithm:UPDate:WINDow
ALGorithm:UPDate:WINDow <num_updates> specifies how many updates may
need to be performed during phase 2 (UPDATE). The DSP will process this command
and assign a constant window of time for UPDATE.
Parameters
Comments •
The default value for <num_updates> is 20. If it is known that fewer updates
may be needed, specifying a smaller number will result in slightly greater loop
execution speeds.
•
This command creates a time interval in which to perform all pending algorithm
and variable updates. To keep the loop times predictable and stable, the time
interval for UPDATE is constant. That is, it exists for all active algorithms, each
time they are executed whether or not an update is pending.
•
*RST Condition: ALG:UPD:WIND 20
•
When Accepted: Before INIT only.
•
Send with VXIplug&play Function: hpe1422_cmd(...)
Usage
A maximum of eight variables will need to be updated during run-time.
ALG:UPD:WIND 8
Parameter
Name
Parameter
Type
Range of
Values
Default
Units
num_updates numeric (int16) 1 - 512 none