diff --git a/README.md b/README.md
index 2d18ce1e..4f2d9093 100644
--- a/README.md
+++ b/README.md
@@ -481,6 +481,15 @@ Send for example `8386` as Downlink on Port 2 to get battery status and time/dat
 0x14 set payload mask
 
 	byte 1 = sensor data payload mask (0..255, meaning of bits see above)
+        0x01 = GPS_DATA
+        0x02 = ALARM_DATA
+        0x04 = MEMS_DATA
+        0x08 = COUNT_DATA (default)
+        0x10 = SENSOR_1_DATA (ENS-COUNTS)
+        0x20 = SENSOR_2_DATA
+        0x40 = SENSOR_3_DATA
+        0x80 = BATT_DATA
+    bytes can be combined eg COUNT_DATA ;SENSOR_1_DATA ;BATT_DATA: `0x08 | 0x10 |0x80 = 0x98`
 
 0x15 set BME data on/off