def set_pv_value(self, name, value, wait=False, timeout=TIMEOUT):
"""Set the PV to a value.
When getting a PV value this call should be used, unless there is a special requirement.
Parameters:
name - the PV name
value - the value to set
wait - wait for the value to be set before returning
"""
name = MYPVPREFIX + ':' + name
if name not in CACHE.keys():
chan = CaChannel(name)
chan.setTimeout(TIMEOUT)
#Try to connect - throws if cannot
chan.searchw()
CACHE[name] = chan
else:
chan = CACHE[name]
if wait:
chan.putw(value)
else:
def putCB(epics_args, user_args):
#Do nothing in the callback
pass
ftype = chan.field_type()
ecount = chan.element_count()
chan.array_put_callback(value, ftype, ecount, putCB)
chan.flush_io()
class pv():
# Wrapper for associating CaChannel class to specific PV using its name
def __init__(self, pvname):
try:
self.pv = CaChannel()
self.pv.searchw(pvname)
self.alarm_status = "n/a" # used to store severity provided by callback
self.alarm_severity = "n/a" # used to store severity provided by callback
except :
raise Exception("****** PV not found - "+pvname+" ******")
#return pv
# Wrapper for putw() function - writing a value to PV and waiting for input records to scan (update their value)
def write(self, *args):
try:
if len(args) == 2: # arguments: value, scan_time
self.pv.putw(args[0])
time.sleep(args[1])
if len(args) == 3: # arguments: value, scan_time, type
if args[2] == "STRING":
self.pv.putw(args[0],ca.DBR_STRING)
else:
raise Exception("Type "+ str(args[3]) +" not recognized")
time.sleep(args[1])
print("***W: Set PV "+self.pv.name()+" to "+str(args[0]))
except:
print("Could not set PV "+self.pv.name()+" to "+str(args[0]))
# Similar to write() except it does not print output when successfully sets the value
# Useful for setUp and tearDown methods
def write_silent(self, *args):
try:
if len(args) == 2: # arguments: value, scan_time
self.pv.putw(args[0])
time.sleep(args[1])
if len(args) == 3: # arguments: value, scan_time, type
if args[2] == "STRING":
self.pv.putw(args[0],ca.DBR_STRING)
else:
raise Exception("Type "+ str(args[3]) +" not recognized")
time.sleep(args[1])
except:
print("Could not set PV "+self.pv.name()+" to "+str(args[0]))
# Wrapper for getw()
def read(self, *args):
if len(args) == 1:
if args[0] == "STRING":
val = self.pv.getw(ca.DBR_STRING)
else:
raise Exception("Type "+ str(args[3]) +" not recognized")
print("***R: Read PV "+self.pv.name()+" value "+str(val))
return val
else:
val = self.pv.getw()
print("***R: Read PV "+self.pv.name()+" value "+str(val))
return val
# Wrapper for getw() with CALLBACK for alarm status/severity
def read_alarm(self):
self.pv.array_get_callback(ca.dbf_type_to_DBR_STS(self.pv.field_type()), None, Callback, self)
self.pv.flush_io()
for i in range(20):
self.pv.pend_event()
# Wrapper for name()
def name(self):
return self.pv.name()
