i want to communicate with 'TestEquity1000' temperature chamber by using 'pyserial' - python-3.x

Question

i want to set and get temperature of serial device (testequity1000) by using pyserial but not able to communicate.
cable used RS232
python 3.7
import serial
port = 'COM20'
` serial_comunication = serial.Serial(port, baudrate=9600, timeout=1)
answer = serial_comunication.read(400)
print(answer)
NEW_TEMPERATURE=45
set_temp=serial_comunication.write(b'NEW_TEMPERATURE')
print(set_temp)
abc=serial_comunication.close()
print(abc)
results:
b''
15
None
can't understand these result

Answer 1

Your device seems to be able to communicate on the RS232 bus but you have to use Modbus instead of the raw serial.
Quoting from the manual:
The F4 Temperature Controller has an RS-232C interface. A DB-9
connector is located on the rear panel. It is wired to accommodate a
null-modem cable. To communicate with the controller from a PC, you
need to run software that uses the Modbus RTU protocol. Each
controller function has a “register” number which can be read or
written to (when applicable). These registers are listed Chapter Seven
of the “Series F4 User’s Manual”. RS-232C Modbus programming resources
and LabVIEW drivers can be downloaded from
http://chamber.testequity.com/rs232.html
Common Modbus Registers
-Actual chamber temperature reading is register 100 (Input 1 Value).
-Actual chamber humidity reading is register 104 (Input 2 Value).
-Static temperature set point is register 300 (Set Point 1).
-Static humidity set point is register 319 (Set Point 2). •
-Temperature set point during a profile is register 4122 (Set Point 1, Current Profile Status).
-Humidity set point during a profile is register 4123 (Set Point 2, Current Profile Status).
-Decimal points are implied. For example, 1005 is actually 100.5 and -230 is -23.0.
Based on these details you can use pymodbus instead. A good starting point is this example.
You can install the package with: pip install pymodbus
So, if you want to read the Actual Chamber Temperature you need to write something similar to this:
#!/usr/bin/env python
# Pymodbus Synchronous Client Examples
# --------------------------------------------------------------------------- #
# import the various server implementations
# --------------------------------------------------------------------------- #
from pymodbus.client.sync import ModbusSerialClient as ModbusClient
# --------------------------------------------------------------------------- #
# configure the client logging
# --------------------------------------------------------------------------- #
import logging
FORMAT = ('%(asctime)-15s %(threadName)-15s '
'%(levelname)-8s %(module)-15s:%(lineno)-8s %(message)s')
logging.basicConfig(format=FORMAT)
log = logging.getLogger()
log.setLevel(logging.DEBUG)
UNIT = 0x1
# ------------------------------------------------------------------------#
# choose the client you want
# ------------------------------------------------------------------------#
client = ModbusClient(method='rtu', port='COM20', timeout=1, baudrate=19200)
client.connect()
# ----------------------------------------------------------------------- #
# example requests
# ----------------------------------------------------------------------- #
rr = client.read_holding_registers(100, 1, unit=UNIT) #Actual chamber temperature reading
print(rr.registers[0])
# ----------------------------------------------------------------------- #
# close the client
# ----------------------------------------------------------------------- #
client.close()
You might need to change the default baudrate (according to the manual 19200) and/or the Modbus UNIT ID (UNIT 1 is the default value).

Answer 2

Hello I actually just finished using a little something in python. TestEquity chamber for the RS-232 you need to use modbus RTU protocol.
I'm using minimalmodbus. The other thing is that you need to make sure that you are using a null modem Tx and Rx need to be swapped in the DB9 connector.
Check the baudrate and slave address in setup, communications.
My code is here:
import minimalmodbus
TE1007C = minimalmodbus.Instrument("COM5", 1)
# Set baudrate
TE1007C.serial.baudrate = 9600
temp = TE1007C.read_register(100, 1, signed=True)
print(temp)
To set a temperature use write_register(). There are other registers that can be use.