Modifying Running Algorithm Variables; Updating Algorithm Variables And Coefficients; Enabling And Disabling Algorithms - VXI VT1422A User Manual

Modifying Running Algorithm Variables

Updating
Algorithm Variables
and Coefficients
Enabling and
Disabling
Algorithms
138 Programming the VT1422A for Data Acquisition and Control
The values sent with the ALG:SCALAR and ALG:ARRAY command are
kept in the Update Queue until an ALGorithm:UPDate command is received.
ALG:UPD
Updates are performed during phase 2 of the instrument operation cycle
(see Figure 4-7 on page 132). The UPDate:WINDow <num_updates>
command can be used to specify how many updates need to be performed
during phase 2 (UPDATE phase) and assigns a constant window of time to
accomplish all of the updates that will be made. The default value for
<num_updates> is 20. Fewer updates (shorter window) means slightly faster
loop execution times. Each update takes approximately 1.4
To set the Update Window to allow 10 updates in phase 2:
ALG:UPD:WIND 10
A way to synchronize variable updates with an external event is to send the
ALGorithm:UPDate:CHANnel '<dig_chan/bit>' command.
•
The <dig_chan/bit> parameter specifies the digital channel/bit that
controls execution of the update operation.
When the ALG:UPD:CHAN command is received, the module checks the
current state of the digital bit. When the bit next changes state, pending
updates are made in the next UPDATE Phase.
ALG:UPD:CHAN 'I133.B0'
For VXIplug&play Users: Use the functions hpe1422_algArray,
hpe1422_algScal to send new values to algorithm variables and
hpe1422_cmd to send the ALG:UPD... SCPI command. See the VT1422A
plug&play driver Help file.
An algorithm is enabled by default when it is defined. To enable or disable
an algorithm, use the ALG:STATe <alg_name>, ON | OFF command.
When an individual algorithm is enabled, it executes when the module is
triggered. When disabled, the algorithm does not execute.
NOTE
The command ALG:STATE <alg_name>, ON | OFF does not take effect
until an ALG:UPDATE command is received. This allows multiple
ALG:STATE commands to be sent with a synchronized effect.
cause changes to take place
μ
s.
allows slightly faster execution
than default of 20 updates
perform updates when bit zero
of VT1533A at channel 133
changes state
Chapter 4