do the whole RS485 DE handling in Python

src/CommunicationProcessor.py

@@ -4,6 +4,7 @@ import RS485Ext
 import RegisterDatapoint
 from pymodbus.client.sync import ModbusSerialClient
 import wiringpi
+import MyRS485
 
 
 ERROR_PIN = 29
@@ -19,8 +20,10 @@ class CommunicationProcessor(threading.Thread):
         self.daemon = True
 
     def __getSerial(self):
-        return RS485Ext.RS485Ext(port=self.config.serialPort, baudrate=self.config.serialBaudRate, stopbits=1,
-                                 timeout=1)
+        # return RS485Ext.RS485Ext(port=self.config.serialPort, baudrate=self.config.serialBaudRate, stopbits=1,
+        #                         timeout=1)
+        return MyRS485.MyRS485(port=self.config.serialPort, baudrate=self.config.serialBaudRate, stopbits=1,
+                               timeout=1)
 
 
     def run(self):

src/MyRS485.py

@@ -0,0 +1,26 @@
+import serial
+import serial.serialutil
+import ctypes
+import wiringpi
+import array
+import fcntl
+import termios
+
+DE_PIN = 0
+
+class MyRS485(serial.Serial):
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        wiringpi.wiringPiSetup()
+        wiringpi.pinMode(DE_PIN, wiringpi.OUTPUT)
+        self.buf = array.array('h', [0])
+
+    def write(self, b):
+        wiringpi.digitalWrite(DE_PIN, wiringpi.HIGH)
+        super.write(b)
+        while True:
+            fcntl.ioctl(self.fileno(), termios.TIOCSERGETLSR, self.buf, 1)
+            if self.buf[0] & termios.TIOCSER_TEMT:
+                break
+        wiringpi.digitalWrite(DE_PIN, wiringpi.LOW)
+