示波器修改：visa连接方式+截图保存

UIShare/GlobalVariable/DeviceHealthMonitor.cs

@@ -124,6 +124,11 @@ namespace UIShare.GlobalVariable
                     {
                         alive = await ProbeTcpDeviceAsync(tcpDevice);
                     }
+                    // VISA 设备同理：IsConnected 仅表示会话对象存在，主动探活以检测死会话
+                    else if (alive && device is Visa visaDevice)
+                    {
+                        alive = await ProbeVisaDeviceAsync(visaDevice);
+                    }
 
                     if (alive)
                     {
@@ -176,6 +181,26 @@ namespace UIShare.GlobalVariable
             }
         }
 
+        /// <summary>
+        /// 对 VISA 设备执行轻量级主动探活（SCPI *IDN?）。
+        /// <para>通过 WriteReadAsync 内部获取 _commLock，与监控采样天然串行化；
+        /// 死会话将在 VISA 自身的 IOTimeout 内抛出异常，返回 false 触发重连。</para>
+        /// </summary>
+        /// <returns>true: 探活成功（会话确实存活）; false: 探活失败（死会话）</returns>
+        private async Task<bool> ProbeVisaDeviceAsync(Visa visaDevice)
+        {
+            try
+            {
+                using var probeCts = new CancellationTokenSource(TimeSpan.FromSeconds(2));
+                string resp = await visaDevice.WriteReadAsync("*IDN?\n", "\n", probeCts.Token);
+                return !string.IsNullOrWhiteSpace(resp);
+            }
+            catch
+            {
+                return false;
+            }
+        }
+
         /// <summary>
         /// 重连单个设备。
         /// <para>