diff --git a/datamanager.cpp b/datamanager.cpp
index e759e73..65dddb5 100644
--- a/datamanager.cpp
+++ b/datamanager.cpp
@@ -67,16 +67,6 @@ void DataManager::appendDataPoint(const QVector<int> &values)
 {
     if (!m_recording) return;
 
-    if (!m_headerWritten) {
-        // 写入表头
-        QStringList headers;
-        for (int i = 0; i < 16; ++i) {
-            headers << QString("ch%1").arg(i);
-        }
-        m_stream << headers.join(",") << "\n";
-        m_headerWritten = true;
-    }
-
     QStringList parts;
     for (int v : values) {
         parts << QString::number(v);
diff --git a/plotwidget.cpp b/plotwidget.cpp
index adfb241..af3adaa 100644
--- a/plotwidget.cpp
+++ b/plotwidget.cpp
@@ -26,7 +26,7 @@ PlotWidget::PlotWidget(QWidget *parent)
     , m_dirty(true)
 {
     m_data.resize(16);
-    m_channelVisible.fill(true, 16);
+    m_channelVisible.fill(false, 16);
     m_colors = defaultColors();
 
     setMouseTracking(true);
@@ -149,6 +149,10 @@ void PlotWidget::autoRangeY()
         }
     }
 
+    if (globalMax < globalMin) {
+        // 没有可见通道或没有数据
+        return;
+    }
     if (globalMax - globalMin < 1.0) {
         globalMin -= 50;
         globalMax += 50;