Total Machine time

#!/usr/bin/python

import time
import hal

fname = "timelog.txt"
sumlog = "time.txt"

delta_t = 1 # seconds poll interval, hold inputs at least this long
f = open(fname,mode="a+") # a: append or create if file doesnt exist
h = hal.component("timelog")
h.newpin("active",hal.HAL_BIT,hal.HAL_IN)
h.newpin("seconds",hal.HAL_U32,hal.HAL_OUT)
h.newpin("minutes",hal.HAL_U32,hal.HAL_OUT)
h.newpin("hours",hal.HAL_U32,hal.HAL_OUT)
h.ready()

try:
        f2= open(sumlog,mode="r+")
        runtime=float(f2.readline())
        f2.close()
except:
        f2= open(sumlog,mode="w+")
        runtime=0.0
        f2.write(str(runtime))
        #f3.flush()
        f2.truncate()
        f2.close()


m, s = divmod(runtime, 60)
hr, m = divmod(m, 60)
#print(hr,m,s)
h["seconds"]=s
h["minutes"]=m
h["hours"]=hr
old_start_pin_value = False
t_start = time.time()
t_begin = time.time()

msg = ("Begin %s\n" % time.ctime())
f.write(msg)
f.flush()
started = False
while True:
    time.sleep(delta_t)
    #print h["active"]
    start_pin_value = h["active"]
    if start_pin_value != old_start_pin_value:
        print("changed")
        if started:
            started = False
            print("timer off")
            t_now = time.time()
            msg = ("Stop:  %s Elapsed: %f\n" % (time.ctime(),t_now - t_start))
            f.write(msg)
            f.flush()
            runtime=seconds
            savetime=str(seconds)
            print savetime
            f2= open(sumlog,mode="w+")
            f2.write(savetime)
            #f3.flush()
            f2.truncate()
            f2.close()
        else:
            started = True
            print("timer on")
            msg = ("Start: %s\n" %time.ctime())
            f.write(msg)
            f.flush()
            t_start = time.time()
            f2= open(sumlog,"r")
            runtime=float(f2.readline())
            f2.close()
            print runtime

    if start_pin_value: 
        seconds= runtime+(time.time() - t_start)
        m, s = divmod(seconds, 60)
        hr, m = divmod(m, 60)
        h["seconds"]=s
        h["minutes"]=m
        h["hours"]=hr
    old_start_pin_value = start_pin_value