I was just about to hit the hay and noticed your post. If you still need help tomorrow I can try.
Looking VERY briefly at your code, the timeout is very short and there is a debug setting that is very helpful so try
#!/usr/bin/env python
import minimalmodbus
instrument = minimalmodbus.Instrument('/dev/ttyUSB0', 1) # port name, slave address (in decimal)
#instrument.serial.port # this is the serial port name
instrument.serial.baudrate = 2400 # Baud
#instrument.serial.bytesize = 8
#instrument.serial.parity = serial.PARITY_NONE
#instrument.serial.stopbits = 1
instrument.serial.timeout = 1.0 # seconds
instrument.debug = True
#print instrument
status = instrument.read_register(0020, 1) # Registernumber, number of decimals
print status
also review the register address in the function call, it needs to be the decimal address eg 0x0600 = 1536, so 0020 might be 32 perhaps?
see Autometers DDSD285 Smart Meter Modbus RS485 interfacing and monitoring
we have just been discussing this tonight.
I also have a modbus heatmeter here, I made some progress with it today, it’s not the same model, but it looks quite similar. I will look at your spec sheet tomorrow if I can.
Please add a link to the listing for this heatmeter, I want to find another cheap supplier.