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"""""
Code for monitoring and controlling temperature in the Maxwell FT200 controller using the Modbus RS485 protocol
@author: Lois Orosa
"""""
import minimalmodbus as mm, serial, time
import time
import os
import sys
import pathlib
class FT200:
"""
Controls and monitors the Maxwell FT200 tempoerature controller
"""
READ_ERROR = -999
WRITE_ERROR = -998
def __init__(self, _baud=9600, _ft200_addr=1, _temp_tolerance=2):
self.baud = _baud
self.write_reg = 5 # Write register
self.read_reg = 0 # Read register
self.ft200_addr = _ft200_addr # Address of the device (by default is 1)
self.temp_tolerance = _temp_tolerance # Temperature tolerance. By default, we consider that we reach the target value if the measured value is within +-0.2C
try:
self.device = self.findDevice() # Get the USB-RS485 device
print("USB-RS485 Device: "+str(self.device))
self.instrument = mm.Instrument(self.device , 3 , debug = False)
self.instrument.serial.baudrate = self.baud
self.instrument.address = self.ft200_addr
self.instrument.serial.timeout = 1
self.instrument.serial.parity = serial.PARITY_NONE
self.instrument.mode = mm.MODE_RTU
print("Device "+self.device+": conected")
except:
raise
# Automatically find the USB-RS485 Device
def findDevice(self):
'''
Find the USB-RS485 device
This function might raise two exceptions:
-> NameError: There is more than 1 USB-RS485 device, or other USB device has a similar name as the USB-RS485 device
-> IOError: Device not found.
'''
DEVICENAME = "1a86_USB"
name = ''
while True:
path = pathlib.Path(__file__).parent.absolute()
f = os.popen(str(path)+"/usb_dev_path.sh")
for device in f:
if DEVICENAME in device:
if name == '':
name = device.split()[0]
else:
raise NameError("There are at least two USB devices whose name contains "+str(DEVICENAME))
if name == '':
raise IOError("Device not found.")
return name
# Read Temperature from FT200
# The output value has 1 decimal, and it is multiplied by 10
# E.g., data= 102 represents a temperature of 10.2C
def readTemp(self):
try:
data = self.instrument.read_register(self.read_reg, functioncode=3)
return data
except IOError:
print("Failed to read from instrument")
return self.READ_ERROR
# Check if the temperature reached a value
# The input value has 1 decimal, and it is multiplied by 10
# E.g., data= 102 represents a temperature of 10.2C
def isTemp(self, temperature):
try:
data = self.instrument.read_register(self.read_reg, functioncode=3)
if data >= (temperature-self.temp_tolerance) and data <= (temperature+self.temp_tolerance):
return True
else:
return False
except IOError:
print("Failed to read from instrument")
return False
# Set Temperature FT200
# The value should be a integer, and it should be the temperature value with 1 decimal multiplied by 10
# E.g., value= 102 represents a temperature of 10.2C
def setTemp(self, value):
try:
self.instrument.write_register(self.write_reg, value, functioncode=6)
except IOError:
print("Failed to write to instrument")
return self.WRITE_ERROR
return 0
# Set the temperature and wait for the temperature to be stable
# Optimized version that reach the target temperature earlier
# The value should be a integer, and it should be the temperature value with 1 decimal multiplied by 10
# E.g., value= 102 represents a temperature of 10.2C
def autoSetAndWait(self, temperature, debug = False):
acceleration_factor = 5
stability = 10 # Iterations that the temperature needs to be stable
time_sleep = 1 # 1 second wait per loop iteration
stable_count = stability # Counter for taking into account the stability of the temperature
stable_margin = 20 # We do not change the set temperature if we are within 2C from the target
optTemp = temperature
self.setTemp(optTemp) # Set the temperature
curTemp = self.readTemp() # Read the temperature
if debug:
print("[TEMPERATURE] current: "+str(curTemp/10.0)+", goal: "+str(temperature/10.0)+", programmed: "+str(optTemp/10.0))
while (((curTemp > (temperature + self.temp_tolerance)) or (curTemp < (temperature - self.temp_tolerance))) or (stable_count!=0)):
if debug:
print("[TEMPERATURE] current: "+str(curTemp/10.0)+", goal: "+str(temperature/10.0)+", programmed: "+str(optTemp/10.0)+", stable_count: "+str(stable_count))
prev_optTemp = optTemp
if (temperature - curTemp) > 0: #(stable_margin): # If we are far away more than 2C
optTemp = temperature + (temperature - curTemp)*acceleration_factor # Optimization to accelerate convergence
else:
optTemp = temperature
if optTemp != prev_optTemp:
self.setTemp(optTemp) # Set temperature only if different from the previous iteration
time.sleep(time_sleep) # WAit for a while
curTemp = self.readTemp() # Read the temperature
while (curTemp == self.READ_ERROR): # If there is an error, read again
curTemp = self.readTemp()
# Five iterations in the range
if (curTemp > (temperature + self.temp_tolerance)) or (curTemp < (temperature - self.temp_tolerance)):
stable_count = stability
else:
stable_count -= 1 # The temperature has to remain stable for a while
def autoSetAndWait_2(self, temperature, debug = False):
acceleration_factor = 150
stability = 10 # Iterations that the temperature needs to be stable
time_sleep = 1 # 1 second wait per loop iteration
stable_count = stability # Counter for taking into account the stability of the temperature
stable_margin = 5 # We do not change the set temperature if we are within 2C from the target
optTemp = temperature
self.setTemp(optTemp) # Set the temperature
curTemp = self.readTemp() # Read the temperature
if debug:
print("[TEMPERATURE] current: "+str(curTemp/10.0)+", goal: "+str(temperature/10.0)+", programmed: "+str(optTemp/10.0))
while (((curTemp > (temperature + self.temp_tolerance)) or (curTemp < (temperature - self.temp_tolerance))) or (stable_count!=0)):
if debug:
print("[TEMPERATURE] current: "+str(curTemp/10.0)+", goal: "+str(temperature/10.0)+", programmed: "+str(optTemp/10.0)+", stable_count: "+str(stable_count))
prev_optTemp = optTemp
if abs(temperature - curTemp) > (stable_margin): # If we are far away more than 2C
if temperature > curTemp:
optTemp = temperature + acceleration_factor # Optimization to accelerate convergence
else:
optTemp = temperature - acceleration_factor # Optimization to accelerate convergence
else:
optTemp = temperature
time.sleep(time_sleep) # WAit for a while
curTemp = self.readTemp() # Read the temperature
while (curTemp == self.READ_ERROR): # If there is an error, read again
curTemp = self.readTemp()
# Five iterations in the range
if (curTemp > (temperature + self.temp_tolerance)) or (curTemp < (temperature - self.temp_tolerance)):
stable_count = stability
else:
stable_count -= 1 # The temperature has to remain stable for a while
if __name__ == '__main__':
## Example of how to use the FT200 class
try:
tc = FT200()
except Exception as error:
print("[ERROR] "+ repr(error))
sys.exit(0)
# Temperature
value = int(sys.argv[1]) * 10
print(value)
print(tc.readTemp())
tc.autoSetAndWait(value,True)
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