works, but license issues due to bcm2835 lib

snippets/test1.py

@@ -1,5 +1,6 @@
 import serial.rs485
 ser=serial.rs485.RS485(port='/dev/ttyAMA0',baudrate=2400)
 ser.rs485_mode = serial.rs485.RS485Settings(False, True)
-ser.write('a test'.encode('utf-8'))
+while True:
+    ser.write('a test'.encode('utf-8'))
 

snippets/test5.py

@@ -0,0 +1,18 @@
+from pymodbus.client.sync import ModbusSerialClient
+import serial.rs485
+import RS485Ext
+
+#ser=serial.rs485.RS485(port='/dev/ttyAMA0',baudrate=1200)
+#ser.rs485_mode = serial.rs485.RS485Settings(rts_level_for_tx=False, 
+#                                            rts_level_for_rx=True,
+#                                            delay_before_tx=0.005,
+#                                            delay_before_rx=-0.0)
+ser=RS485Ext.RS485Ext(port='/dev/ttyAMA0', baudrate=1200)
+
+client = ModbusSerialClient(method='rtu')
+client.socket = ser
+client.connect()
+result = client.read_holding_registers(address=0x2000, count=2, unit=1)
+print(result)
+print(result.registers)
+client.close()