diff --git a/inc/protocol.h b/inc/protocol.h
--- a/inc/protocol.h
+++ b/inc/protocol.h
@@ -43,7 +43,7 @@ typedef enum {
     FREQ_INPUT = 0x0002,
     ANALOG_INPUT = 0x0003,
     DIGITAL_OUTPUT = 0x0004,
-    FREQ_OUTPUT = 0x0005,
+    PWM_OUTPUT = 0x0005,
     ANALOG_OUTPUT = 0x0006,
     AIR_TEMP = 0x0007,
     AIR_HUMIDITY = 0x0008,