sources

src/ModbusHandler.py

@@ -0,0 +1,77 @@
+from pymodbus.client.sync import ModbusTcpClient as ModbusClient
+from pymodbus.exceptions import ModbusIOException
+from time import sleep
+import threading
+
+
+MODBUS_CLIENT = '172.16.2.157'
+MODBUS_REFRESH_PERIOD = 0.25
+
+
+
+def modbusHandler(processImage):
+    client = ModbusClient(MODBUS_CLIENT)
+
+    try:
+        client.connect()
+
+        res = client.read_holding_registers(0x1010, 4)
+        if isinstance(res, ModbusIOException):
+            raise Exception(processImage)
+
+        if len(res.registers) != 4:
+            raise Exception("Unexpected number of registers for process image ({})".format(len(res.registers)))
+
+        (analogOutputBits, analogInputBits, digitalOutputBits, digitalInputBits) = res.registers
+        print(f"AO: {analogOutputBits}, AI: {analogInputBits}, DO: {digitalOutputBits}, DI: {digitalInputBits}")
+
+        processImage.init(digitalOutputBits, digitalInputBits, analogInputBits)
+
+        reg = client.read_coils(0, digitalOutputBits)
+        if isinstance(reg, ModbusIOException):
+            raise Exception(reg)
+        with processImage:
+            processImage.setCoils(reg.bits)
+
+        while True:
+            try:
+                if not client.is_socket_open():
+                    client.connect()
+
+                reg = client.read_input_registers(0, analogInputBits // 8)
+                print("M0: ".format(type(reg)))
+                if isinstance(reg, ModbusIOException):
+                    raise Exception(reg)
+                analogInputs = reg.registers
+                print("M1: ".format(reg.registers))
+
+                reg = client.read_discrete_inputs(0, digitalInputBits)
+                if isinstance(reg, ModbusIOException):
+                    raise Exception(reg)
+                discreteInputs = reg.bits
+                print("M2: ".format(reg.bits))
+
+                coils = None
+                with processImage:
+                    processImage.setAnalogsInputs(analogInputs)
+                    processImage.setDiscreteInputs(discreteInputs)
+                    if processImage.hasPendingInputChanges():
+                        processImage.notify()
+                    if processImage.hasPendingOutputChanges:
+                        coils = processImage.getCoils()
+
+                if coils:
+                    reg = client.write_coils(0, coils)
+                    if isinstance(reg, ModbusIOException):
+                        raise Exception(reg)
+
+            except Exception as e:
+                print("Exception in inner modbus handler loop: {}".format(e))
+                client.close()
+            finally:
+                sleep(MODBUS_REFRESH_PERIOD)
+
+    except Exception as e:
+        print("Exception in modbus handler: {}".format(e))
+    finally:
+        client.close()