From 1108427023c6cf9b82684106e5c780a41022dc55 Mon Sep 17 00:00:00 2001
From: Lorenz Stechauner <lorenz.stechauner@necronda.net>
Date: Wed, 25 Feb 2026 10:57:44 +0100
Subject: [PATCH] [#74] Weighing: Try to reconnect tcp scales on first error

---
 Elwig/Helpers/Weighing/GassnerScale.cs  | 13 ++++++++++---
 Elwig/Helpers/Weighing/Scale.cs         | 10 ++++++++++
 Elwig/Helpers/Weighing/SysTecITScale.cs | 17 +++++++++++++----
 3 files changed, 33 insertions(+), 7 deletions(-)

diff --git a/Elwig/Helpers/Weighing/GassnerScale.cs b/Elwig/Helpers/Weighing/GassnerScale.cs
index a6ff07d..32406bb 100644
--- a/Elwig/Helpers/Weighing/GassnerScale.cs
+++ b/Elwig/Helpers/Weighing/GassnerScale.cs
@@ -53,9 +53,16 @@ namespace Elwig.Helpers.Weighing {
             return line[1..^1];
         }
 
-        protected async Task<WeighingResult> Weigh(bool incIdentNr) {
-            await SendCommand(incIdentNr ? '\x05' : '?');
-            string record = await ReceiveResponse();
+        protected async Task<WeighingResult> Weigh(bool incIdentNr, bool retry = true) {
+            string record;
+            try {
+                await SendCommand(incIdentNr ? '\x05' : '?');
+                record = await ReceiveResponse();
+            } catch (IOException) {
+                if (!retry || Tcp == null) throw;
+                ReconnectTcp();
+                return await Weigh(incIdentNr, false);
+            }
             if (record.Length != 45)
                 throw new FormatException("Invalid response from scale: Received record has invalid size");
             var line = record[2..];
diff --git a/Elwig/Helpers/Weighing/Scale.cs b/Elwig/Helpers/Weighing/Scale.cs
index f387cfa..e472613 100644
--- a/Elwig/Helpers/Weighing/Scale.cs
+++ b/Elwig/Helpers/Weighing/Scale.cs
@@ -10,6 +10,7 @@ namespace Elwig.Helpers.Weighing {
 
         protected enum Output { RTS, DTR, OUT1, OUT2 };
 
+        protected readonly string Connection;
         protected SerialPort? Serial = null;
         protected SerialPort? ControlSerialEmpty = null, ControlSerialFilling = null;
         protected TcpClient? Tcp = null;
@@ -37,6 +38,7 @@ namespace Elwig.Helpers.Weighing {
         }
 
         protected Scale(string cnx, string? empty, string? filling, int? limit, string? log, bool softFail = false, bool failSilent = false) {
+            Connection = cnx;
             if (cnx.StartsWith("serial:")) {
                 try {
                     Serial = Utils.OpenSerialConnection(cnx);
@@ -95,6 +97,14 @@ namespace Elwig.Helpers.Weighing {
             GC.SuppressFinalize(this);
         }
 
+        protected void ReconnectTcp() {
+            if (Connection.StartsWith("tcp:")) {
+                Tcp = Utils.OpenTcpConnection(Connection);
+                Stream = Tcp.GetStream();
+                Reader = new(Stream, Encoding.ASCII, false, 512);
+            }
+        }
+
         protected static Output? ConvertOutput(string? value) {
             return value switch {
                 null => null,
diff --git a/Elwig/Helpers/Weighing/SysTecITScale.cs b/Elwig/Helpers/Weighing/SysTecITScale.cs
index b3ffd4a..7dc7bb3 100644
--- a/Elwig/Helpers/Weighing/SysTecITScale.cs
+++ b/Elwig/Helpers/Weighing/SysTecITScale.cs
@@ -33,7 +33,9 @@ namespace Elwig.Helpers.Weighing {
         protected async Task<string> ReceiveResponse() {
             var line = await Reader.ReadUntilAsync("\r\n");
             if (LogPath != null) await File.AppendAllTextAsync(LogPath, line);
-            if (line == null || line.Length < 4 || !line.StartsWith('<') || !line.EndsWith(">\r\n")) {
+            if (line == null) {
+                throw new IOException("Verbindung zu Waage verloren");
+            } else if (line.Length < 4 || !line.StartsWith('<') || !line.EndsWith(">\r\n")) {
                 throw new FormatException("Invalid response from scale");
             }
 
@@ -72,9 +74,16 @@ namespace Elwig.Helpers.Weighing {
             return line[1..^3];
         }
 
-        protected async Task<WeighingResult> Weigh(bool incIdentNr) {
-            await SendCommand(incIdentNr ? $"RN{InternalScaleNr}" : $"RM{InternalScaleNr}");
-            string record = await ReceiveResponse();
+        protected async Task<WeighingResult> Weigh(bool incIdentNr, bool retry = true) {
+            string record;
+            try {
+                await SendCommand(incIdentNr ? $"RN{InternalScaleNr}" : $"RM{InternalScaleNr}");
+                record = await ReceiveResponse();
+            } catch (IOException) {
+                if (!retry || Tcp == null) throw;
+                ReconnectTcp();
+                return await Weigh(incIdentNr, false);
+            }
             if (record.Length != 62)
                 throw new FormatException("Invalid response from scale: Received record has invalid size");
             var line = record[2..];