dstp_data_fit.py

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"""A shakedown application for the use of the dstp server.  Maybe out of date"""
_rcsid="$Id: dstp_data_fit.py,v 1.4 2003/05/30 13:31:55 mendenhall Release-20030716 $"

import sys
import os

sys.path.append(os.path.join(os.path.dirname(__file__),"data acquisition")) #look in 'data acquisition' folder for needed routines, too

import time
import threading
import array
import traceback
import Numeric
import math

import nati_dstp_basics
import tagged_data
import dstp_async


nati_dstp_basics.UseNumericArray(1) #use Numeric.array instead of array.array as standard format

print "go!"

s=dstp_async.DSTPServer()

data=tagged_data.tagged_data_system() #create a data cache with neatly nameable elements 

#define data types in the cache, and what device is responsible for them, and what format they have:
#data.define_field(<visible_name>, <device>, <internal name on device>, <sample object for this field>, <writable>
#note that for DSTP devices, the <internal name on device> much match the DSTP URL given in labVIEW (not case sensitive)
data.define_field("XY", s, ("xyvals", [array.array('d',[]), array.array('d',[])]), writable=0)
data.define_field("fitparms", s, ("parms", [0,array.array('d'),0.0,array.array('d')]), writable=1)
data.define_field("quit_server", s, ("quit_server", 0), writable=0)

#create a routine to listen for shutdown commands
def quit_server(string):
    if data.quit_server:
        s.close()
#tell the server to pass shutdown commands to this routine
s.listen("quit_server", quit_server)

try:
    loopcount=0

    def run_fit(string):
        global loopcount
        
        try:
            #note that arrays get passed flattened, and with the original dimensioning info in a tuple with the array.  I will fix this later.
            (xl,x),(yl,y)=data.XY
            
            #print x,y 
            loopcount += 1 #make sure each time we send data, this is different, so LabVIEW notices the change
            
            y*=7.0 #bogus data processing (put real fitting here)
            
            data.fitparms=[loopcount,y,math.sqrt(Numeric.sum((y-1)*(y-1))), y-1] #send computed results back to LabVIEW

        except: #clean up on errors
            traceback.print_exc() #dump what went wrong, then close the server so we can edit the program
            s.close()       
            
    #tell the server that any time new data appears in 'xyvals' to call 'run_fit'
    s.listen("xyvals", run_fit)
    
    #start server 
    s.serve()   
        
finally: #clean up on exit or errors
    s.close()
    time.sleep(1)

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