source: pvrrd/rrd_pv.py @ 206

#!/usr/bin/env python

'''
log EPICS data into RRD files
'''

########### SVN repository information ###################
# $Date: 2010-08-18 20:28:25 +0000 (Wed, 18 Aug 2010) $
# $Author: jemian $
# $Revision: 206 $
# $HeadURL$
# $Id: rrd_pv.py 206 2010-08-18 20:28:25Z jemian $
########### SVN repository information ###################

#-------------------------------------------------------------

import os
import time
import sys
import pprint
import rrdtool      # direct calls to rrd tools
import pvwatch      # local support to monitor EPICS PVs

#-------------------------------------------------------------


class rrd_pv:
    '''coordination between an EPICS PV and a RRD database'''

    rrd = None         # corresponding rrd database for this channel
    name = None        # EPICS PV name
    pv = None          # EPICS channel object

    def __init__(self, name, rrd_database_file):
        # define the RRD database file name
        self.rrd = rrd_database_file

        # start the connection with the EPICS process variable
        self.pv = pvwatch.pvwatch(name)

    def update(self):
        '''write the current EPICS value to the RRD database'''
        s = 'N:'+repr(self.pv.value).strip()
        rrdtool.update(self.rrd, s)

    def __str__(self):
        p = "%s" % self.pv
        r = ""
        if not self.rrd == None:
            r = "%s" % rrdtool.info(self.rrd)['last_update']
        return "%s %s" % (p, r)