HP VXI 75000 C Series, User'S And Scpi Programming Manual

Page: 90 / 438

90 Programming the HP E1415 for PID Control Chapter 3
Here’s an example command sequence for Figure 3-9. It assumes that the
FIFO mode was set to BLOCK and that at least one algorithm is sending
values to the FIFO (a PIDB with History_mode set to 1).
following loop reads number of values in FIFO while algorithms executing
loop while "measuring" bit is true
see STAT:OPER:COND bit 4
SENS:DATA:FIFO:COUNT?
query for count of values in
FIFO
input n_values here
if
n_values
>= 16384
Set minimum block size you want
to transfer
SENS:DATA:FIFO:PART? n_values
ask for n_values
input read_data here
Format depends on FORMat
cmd
end if
end while loop
following checks for values remaining in FIFO after "measuring" false
SENS:DATA:FIFO:COUNT?
query for values still in FIFO
input n_values here
if n_values
if any values...
SENS:DATA:FIFO:PART? n_values
input read_data here
get remaining values from FIFO
end if
Reading the Latest FIFO Values (FIFO mode OVER)
In this mode the FIFO always contains the latest values (up to the FIFO’s
capacity of 65,024 values) from running algorithms. In order to read these
values the algorithms must be stopped (use ABORT).This forms a record of
the algorithm’s latest performance. In the OVERwrite mode, the FIFO can
not be read while it is accepting readings from algorithms. Algorithm
execution must be stopped before your application program reads the FIFO.
Here is an example command sequence you can use to read values from the
FIFO after algorithms are stopped (ABORT sent).
SENS:DATA:FIFO:COUNT?
query count of values in FIFO
input n_values here
if n_values
if any values...
SENS:DATA:FIFO:PART? n_values
Format of values set by FORMat
input read_data here
get remaining values from FIFO
end of if
Modifying Running Algorithm Variables
Updating the
Algorithm Variables
and Coefficients
The values sent with the ALG:SCALAR command are kept in the Update
Queue until an ALGorithm:UPDate command is received.
ALG:UPD
cause changes to take place
Updates are performed during phase 2 of the algorithm execution cycle (see
Figure 3-8 on page 86). The UPDate:WINDow <num_updates> command