def _initialise_channel(self, name):
"""Initialises the channel by creating a connection callback.
Args:
name (string): The name of the PV to connect to.
"""
def _block_connection_callback(epics_args, user_args):
connection_state = epics_args[1]
if connection_state == ca.CA_OP_CONN_UP:
print ca.name(epics_args[0]), "UP"
# First time through creates the monitor
if ca.name(epics_args[0]) not in self.curr_values:
self._create_monitor(user_args[0], ca.name(epics_args[0]))
else:
print ca.name(epics_args[0]), "DOWN"
self.curr_lock.acquire()
try:
self.curr_values[ca.name(epics_args[0])] = ("*** disconnected", None)
except:
# Don't care, it is all about releasing the lock
pass
finally:
# Must release lock
self.curr_lock.release()
chan = CaChannel()
chan.setTimeout(EXISTS_TIMEOUT)
print "initialising %s" % name
try:
chan.search_and_connect(name, _block_connection_callback, chan)
chan.pend_event(PEND_EVENT_TIMEOUT)
return chan
except:
print "Could not connect"
return None
def connect_to_names_pv(self):
"""Connects amonitor to the block-server to get the names of the blocks.
"""
def _blocknames_callback(epics_args, user_args):
names = json.loads(dehex_and_decompress(waveform_to_string(epics_args['pv_value'])))
if self.block_names is None or names != self.block_names:
self.block_names = names
print "Updated"
chan = CaChannel("BLOCKNAMES")
chan.searchw("%s%s" % (self.prefix, "CS:BLOCKSERVER:BLOCKNAMES"))
chan.add_masked_array_event(
ca.DBR_CHAR,
None,
ca.DBE_VALUE | ca.DBE_ALARM,
_blocknames_callback)
chan.pend_event(PEND_EVENT_TIMEOUT)
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()
