From eb73beb1cdb6b741481c03a98e9c366938155b36 Mon Sep 17 00:00:00 2001
From: ig <ig ig@devnullmail.com>
Date: Thu, 9 Mar 2023 13:16:26 +0100
Subject: [PATCH] Implement failure resilient TCP connections for Adam and AMPT

---
 .../Lib/Devices/AMPT/AmptCommunicationUnit.cs | 30 ++++++---
 csharp/Lib/Devices/Adam6060/Adam6060Device.cs | 61 ++++++++++++++-----
 2 files changed, 67 insertions(+), 24 deletions(-)

diff --git a/csharp/Lib/Devices/AMPT/AmptCommunicationUnit.cs b/csharp/Lib/Devices/AMPT/AmptCommunicationUnit.cs
index 4238877ac..6491f4e8b 100644
--- a/csharp/Lib/Devices/AMPT/AmptCommunicationUnit.cs
+++ b/csharp/Lib/Devices/AMPT/AmptCommunicationUnit.cs
@@ -27,30 +27,42 @@ public class AmptCommunicationUnit
     {
         try
         {
-            var modbus = OpenConnection();
-            return TryReadStatus(modbus);
+            OpenConnection();
+            return TryReadStatus();
         }
-        catch 
+        catch
         {
-            Modbus?.CloseConnection();
+            CloseConnection();
             return null;
         }
     }
 
-    private ModbusTcpClient OpenConnection()
+    private void CloseConnection()
+    {
+        try
+        {
+            Modbus?.CloseConnection();
+        }
+        catch
+        {
+            // ignored
+        }
+
+        Modbus = null;
+    }
+
+    private void OpenConnection()
     {
         if (Modbus is null)
         {
             var connection = new ModbusTcpConnection(Hostname, Port);
             Modbus = new ModbusTcpClient(connection, SlaveAddress);
         }
-
-        return Modbus;
     }
 
-    private static AmptCommunicationUnitStatus TryReadStatus(ModbusTcpClient modbus)
+    private AmptCommunicationUnitStatus TryReadStatus()
     {
-        var r = modbus.ReadHoldingRegisters(1, 116);
+        var r = Modbus!.ReadHoldingRegisters(1, 116);
 
         var currentFactor = Pow(10.0m, r.GetInt16(73));
         var voltageFactor = Pow(10.0m, r.GetInt16(74));
diff --git a/csharp/Lib/Devices/Adam6060/Adam6060Device.cs b/csharp/Lib/Devices/Adam6060/Adam6060Device.cs
index 09af1a1a0..d910baf41 100644
--- a/csharp/Lib/Devices/Adam6060/Adam6060Device.cs
+++ b/csharp/Lib/Devices/Adam6060/Adam6060Device.cs
@@ -7,31 +7,60 @@ namespace InnovEnergy.Lib.Devices.Adam6060;
 
 public class Adam6060Device
 {
-    private ModbusTcpClient Modbus { get; }
+    public String Hostname     { get; }
+    public UInt16 Port         { get; }
+    public Byte   SlaveAddress { get; }
+    
+    private ModbusTcpClient? Modbus { get; set; }
 
     public Adam6060Device(String hostname, UInt16 port = 5004, Byte slaveAddress = 2)
     {
-        var connection = new ModbusTcpConnection(hostname, port);
-        Modbus = new ModbusTcpClient(connection, slaveAddress);
+        Hostname     = hostname;
+        Port         = port;
+        SlaveAddress = slaveAddress;
+    }
+
+    private void OpenConnection()
+    {
+        if (Modbus is null)
+        {
+            var connection = new ModbusTcpConnection(Hostname, Port);
+            Modbus = new ModbusTcpClient(connection, SlaveAddress);
+        }
     }
 
     public Adam6060Status? ReadStatus()
     {
         try
         {
+            OpenConnection();
             return TryReadStatus();
         }
-        catch (Exception)
+        catch
         {
-            Modbus.CloseConnection();
+            CloseConnection();
             return null;
         }    
     }
 
+    private void CloseConnection()
+    {
+        try
+        {
+            Modbus?.CloseConnection();
+        }
+        catch
+        {
+            // ignored
+        }
+
+        Modbus = null;
+    }
+
     private Adam6060Status TryReadStatus()
     {
-        var inputs = Modbus.ReadDiscreteInputs(DigitalInputsStartRegister, NbDigitalInputs);
-        var relays = Modbus.ReadDiscreteInputs(RelaysStartRegister, NbRelays);
+        var inputs = Modbus!.ReadDiscreteInputs(DigitalInputsStartRegister, NbDigitalInputs);
+        var relays = Modbus!.ReadDiscreteInputs(RelaysStartRegister, NbRelays);
 
         return new Adam6060Status
         {
@@ -55,17 +84,19 @@ public class Adam6060Device
     {
         try
         {
-            Modbus.WriteMultipleCoils(RelaysStartRegister, control.Relay0,
-                                                           control.Relay1,
-                                                           control.Relay2,
-                                                           control.Relay3,
-                                                           control.Relay4,
-                                                           control.Relay5);
+            OpenConnection();
+            
+            Modbus!.WriteMultipleCoils(RelaysStartRegister, control.Relay0,
+                                                            control.Relay1,
+                                                            control.Relay2,
+                                                            control.Relay3,
+                                                            control.Relay4,
+                                                            control.Relay5);
             return true;
         }
-        catch (Exception)
+        catch 
         {
-            Modbus.CloseConnection();
+            CloseConnection();
             return false;
         }
     }