fix(s7): numeric TSAP loads in form, shared TSAP conflict error, Test Connect read detects PUT/GET disabled, pin Int32 ms rounding (#632 #638)

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.S7/S7DriverProbe.cs

@@ -80,7 +80,15 @@ public sealed class S7DriverProbe : IDriverProbe
             sw.Stop();
 
             if (plc.IsConnected)
+            {
+                // A handshake alone passes on a CPU with PUT/GET disabled (S7-1200/1500 default) — every
+                // later read would fail. One minimal read proves data access.
+                if (await CheckDataAccessAsync(
+                        t => plc.ReadBytesAsync(global::S7.Net.DataType.Memory, 0, 0, 2, t), handshakeCts.Token)
+                    is { } denied)
+                    return denied;
                 return new(true, $"S7 connected (CPU {opts.CpuType}, PDU {plc.MaxPDUSize} bytes)", sw.Elapsed);
+            }
 
             return new(false, $"Reachable at {host}:{port} but S7 handshake failed: not connected", null);
         }
@@ -104,6 +112,38 @@ public sealed class S7DriverProbe : IDriverProbe
         }
     }
 
+    /// <summary>
+    ///     Runs one minimal read after the handshake. Returns null when data access works — including when the
+    ///     CPU merely rejects that particular address (MB0 not present / out of range: the connection is fine).
+    ///     PUT/GET-disabled yields the actionable message; any other fault is a probe failure with its message.
+    /// </summary>
+    /// <param name="read">The minimal read.</param>
+    /// <param name="ct">Cancellation token.</param>
+    /// <returns>A failure result, or null on success.</returns>
+    internal static async Task<DriverProbeResult?> CheckDataAccessAsync(Func<CancellationToken, Task<byte[]>> read, CancellationToken ct)
+    {
+        try
+        {
+            await read(ct).ConfigureAwait(false);
+            return null;
+        }
+        catch (OperationCanceledException) { throw; }
+        catch (PlcException pex) when (S7Driver.IsAccessDenied(pex))
+        {
+            return new(false,
+                "S7 connected but data access is denied — enable PUT/GET communication in TIA Portal " +
+                $"(Protection & Security) for this CPU. PLC reported: {pex.Message}", null);
+        }
+        catch (PlcException pex) when (pex.ErrorCode == ErrorCode.ReadData)
+        {
+            return null; // address not available on this CPU — not a connection problem
+        }
+        catch (Exception ex)
+        {
+            return new(false, $"S7 connected but a test read failed: {ex.Message}", null);
+        }
+    }
+
     private static (string host, int port) ExtractTarget(S7DriverOptions opts)
         => (opts.Host, opts.Port);
 }