created test script for modbus. (DH)

tests/minimalmodbus_test.py

@@ -0,0 +1,18 @@
+#!/usr/bin/env python3
+import minimalmodbus
+import serial
+
+slave_address = 0x11
+instrument = minimalmodbus.Instrument('/dev/ttyUSB0', slave_address, close_port_after_each_call=True)  # port name, slave address (in decimal)
+
+instrument.serial.baudrate = 115200
+instrument.serial.bytesize = 8
+instrument.serial.parity   = serial.PARITY_EVEN
+instrument.serial.stopbits = 1
+instrument.serial.timeout  = 0.05          # seconds
+instrument.mode = minimalmodbus.MODE_RTU   # rtu or ascii mode
+instrument.clear_buffers_before_each_transaction = True
+
+# read
+CO2 = instrument.read_register(9, 1, functioncode=4) * 10
+print(CO2)