use v even if it is 0

main.go

@@ -501,9 +501,7 @@ func WriteDatapoint(mytime int64, deveui string, devaddr string, v uint8, h uint
 			vp = 100
 		}
 
-		if v > 0 {
-			sv = fmt.Sprintf("v=%di,vp=%di,", int32(v)*7+2510, vp)
-		}
+		sv = fmt.Sprintf("v=%di,vp=%di,", int32(v)*7+2510, vp)
 
 		s := ""
 		sfw := ""