initial

snippets/test1.py

@@ -0,0 +1,43 @@
+from pymodbus.client.sync import ModbusTcpClient as ModbusClient
+from pymodbus.exceptions import ModbusIOException
+from time import sleep
+
+
+client = ModbusClient('172.16.2.157')
+
+try:
+    client.connect()
+
+    processImage = client.read_holding_registers(0x1010, 4)
+    if isinstance(processImage, ModbusIOException):
+        raise Exception(processImage)
+
+    if len(processImage.registers) != 4:
+        raise Exception("Unexpected number of registers in process image ({})".format(len(processImage.registers)))
+
+    (analogOutputBits, analogInputBits, digitalOutputBits, digitalInputBits) = processImage.registers
+    print(f"AO: {analogOutputBits}, AI: {analogInputBits}, DO: {digitalOutputBits}, DI: {digitalInputBits}")
+
+    while True:
+        reg = client.read_input_registers(0, analogInputBits // 8)
+        if isinstance(reg, ModbusIOException):
+            raise Exception(reg)
+        print(reg.registers)
+
+        reg = client.read_discrete_inputs(0, digitalInputBits)
+        if isinstance(reg, ModbusIOException):
+            raise Exception(reg)
+        print(reg.bits)
+
+        reg = client.read_coils(0, digitalOutputBits)
+        if isinstance(reg, ModbusIOException):
+            raise Exception(reg)
+        print(reg.bits)
+
+        sleep(0.1)
+
+except Exception as e:
+    print("Exception: {}".format(e))
+finally:
+    client.close()
+

snippets/test2.py

@@ -0,0 +1,121 @@
+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
+
+
+coils = []
+shadowCoils = []
+
+discreteInputs = []
+shadowDiscreteInputs = []
+
+analogInputs = []
+shadowAnalogInputs = []
+
+changeCondition = threading.Condition()
+
+
+def modbusHandler():
+    global coils, shadowCoils, discreteInputs, shadowDiscreteInputs, analogInputs, shadowAnalogInputs
+
+
+    client = ModbusClient(MODBUS_CLIENT)
+
+    try:
+        client.connect()
+
+        processImage = client.read_holding_registers(0x1010, 4)
+        if isinstance(processImage, ModbusIOException):
+            raise Exception(processImage)
+
+        if len(processImage.registers) != 4:
+            raise Exception("Unexpected number of registers in process image ({})".format(len(processImage.registers)))
+
+        (analogOutputBits, analogInputBits, digitalOutputBits, digitalInputBits) = processImage.registers
+        print(f"AO: {analogOutputBits}, AI: {analogInputBits}, DO: {digitalOutputBits}, DI: {digitalInputBits}")
+
+        shadowAnalogInputs = [ -1 ] * (analogInputBits // 8)
+        shadowDiscreteInputs = [ -1 ] * digitalInputBits
+
+        reg = client.read_coils(0, digitalOutputBits)
+        if isinstance(reg, ModbusIOException):
+            raise Exception(reg)
+        coils = reg.bits
+        shadowCoils = coils
+
+
+        while True:
+            try:
+                if not client.is_socket_open():
+                    client.connect()
+
+                reg = client.read_input_registers(0, analogInputBits // 8)
+                if isinstance(reg, ModbusIOException):
+                    raise Exception(reg)
+                analogInputs = reg.registers
+
+                reg = client.read_discrete_inputs(0, digitalInputBits)
+                if isinstance(reg, ModbusIOException):
+                    raise Exception(reg)
+                discreteInputs = reg.bits
+
+                if (discreteInputs != shadowDiscreteInputs) or (analogInputs != shadowAnalogInputs):
+                    with changeCondition:
+                        changeCondition.notify()
+
+                if coils != shadowCoils:
+                    reg = client.write_coils(0, shadowCoils)
+                    if isinstance(reg, ModbusIOException):
+                        raise Exception(reg)
+                    coils = shadowCoils
+
+            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()
+
+
+
+def publisher():
+    global coils, shadowCoils, discreteInputs, shadowDiscreteInputs, analogInputs, shadowAnalogInputs
+
+    while True:
+        with changeCondition:
+            changeCondition.wait()
+
+            if discreteInputs != shadowDiscreteInputs:
+                for i in range(len(shadowDiscreteInputs)):
+                    if discreteInputs[i] != shadowDiscreteInputs[i]:
+                        print("di changed: {}, {}".format(i, discreteInputs[i]))
+                shadowDiscreteInputs = discreteInputs
+            
+            if analogInputs != shadowAnalogInputs:
+                for i in range(len(shadowAnalogInputs)):
+                    if analogInputs[i] != shadowAnalogInputs[i]:
+                        print("ai changed: {}, {}".format(i, analogInputs[i]))
+                shadowAnalogInputs = analogInputs
+
+
+
+
+modbusThread = threading.Thread(target=modbusHandler)
+publisherThread = threading.Thread(target=publisher)
+
+modbusThread.start()
+publisherThread.start()
+
+
+
+
+