diff --git a/ShineLAN-X/firmware/include/config.h b/ShineLAN-X/firmware/include/config.h
index 4bce396..255c265 100644
--- a/ShineLAN-X/firmware/include/config.h
+++ b/ShineLAN-X/firmware/include/config.h
@@ -27,7 +27,7 @@
 // ============================================================
 // MODBUS
 // ============================================================
-#define MODBUS_BAUD   115200
+#define MODBUS_BAUD   9600
 #define MODBUS_ADDR   1
 
 // ============================================================
diff --git a/ShineLAN-X/firmware/platformio.ini b/ShineLAN-X/firmware/platformio.ini
index 0ed2786..826935a 100644
--- a/ShineLAN-X/firmware/platformio.ini
+++ b/ShineLAN-X/firmware/platformio.ini
@@ -17,4 +17,6 @@ build_flags =
     -DUSBD_USE_CDC
     -DHAL_PCD_MODULE_ENABLED
     -DUSB_CDC_TRANSMIT_TIMEOUT=3000
+    -DCUSTOM_USBD_PID=0x5740
+    '-DUSB_PRODUCT_STRING="STM32 Virtual COM Port"'
     -I include
diff --git a/ShineLAN-X/firmware/src/main.cpp b/ShineLAN-X/firmware/src/main.cpp
index fb94978..6741c10 100644
--- a/ShineLAN-X/firmware/src/main.cpp
+++ b/ShineLAN-X/firmware/src/main.cpp
@@ -551,7 +551,8 @@ void loop() {
 
     ledSet(LED_BLUE, true);
 
-    bool     usbReady   = (SerialUSB.availableForWrite() == 127);
+    uint8_t  avStart    = SerialUSB.availableForWrite();
+    bool     usbReady   = (avStart >= 8);
     uint8_t  okCount    = 0, failCount = 0;
     uint8_t  lastErr    = 0;
     uint16_t lastErrReg = 0;
@@ -600,9 +601,9 @@ void loop() {
     if (lastErr) g_lastErr = lastErr;
 
     char dbg[64];
-    snprintf(dbg, sizeof(dbg), "ok=%u fail=%u err=0x%02X@%u av=%d rx=%d",
+    snprintf(dbg, sizeof(dbg), "ok=%u fail=%u err=0x%02X@%u avS=%d avE=%d rx=%d",
         okCount, failCount, lastErr, lastErrReg,
-        SerialUSB.availableForWrite(), SerialUSB.available());
+        avStart, SerialUSB.availableForWrite(), SerialUSB.available());
     mqtt.publish("growatt/shinelan/debug", dbg);
 
     ledSet(LED_BLUE, false);