diff --git a/bacnet-stack/include/config.h b/bacnet-stack/include/config.h
index 130e2bde..1c930d57 100644
--- a/bacnet-stack/include/config.h
+++ b/bacnet-stack/include/config.h
@@ -97,7 +97,7 @@
 
 /* some modules have debugging enabled using PRINT_ENABLED */
 #if !defined(PRINT_ENABLED)
-#define PRINT_ENABLED 0
+#define PRINT_ENABLED 1
 #endif
 
 /* BACAPP decodes WriteProperty service requests
diff --git a/bacnet-stack/include/trendlog.h b/bacnet-stack/include/trendlog.h
index b63dda4c..25c26064 100644
--- a/bacnet-stack/include/trendlog.h
+++ b/bacnet-stack/include/trendlog.h
@@ -37,6 +37,92 @@
 extern "C" {
 #endif /* __cplusplus */
 
+/* Error code for Trend Log storage */
+typedef struct tl_error {
+    uint16_t usClass;
+    uint16_t usCode;
+} TL_ERROR;
+
+/* Bit string of up to 32 bits for Trend Log storage */
+
+typedef struct tl_bits {
+    uint8_t  ucLen;         /* bytes used in upper nibble/bits free in lower nibble */
+    uint8_t  ucStore[4];
+} TL_BITS;
+
+/* Storage structure for Trend Log data
+ *
+ * Note. I've tried to minimise the storage requirements here
+ * as the memory requirements for logging in embedded
+ * implementations are frequently a big issue. For PC or
+ * embedded Linux type setupz this may seem like overkill
+ * but if you have limited memory and need to squeeze as much
+ * logging capacity as possible every little byte counts!
+ */
+
+typedef struct tl_data_record {
+    time_t tTimeStamp;     /* When the event occurred */
+    uint8_t ucRecType;     /* What type of Event */
+    uint8_t ucStatus;      /* Optional Status for read value in b0-b2, b7 = 1 if status is used */
+    union {
+        uint8_t  ucLogStatus;   /* Change of log state flags */
+        uint8_t  ucBoolean;     /* Stored boolean value */
+        float    fReal;         /* Stored floating point value */
+        uint32_t ulEnum;        /* Stored enumerated value - max 32 bits */
+        uint32_t ulUValue;      /* Stored unsigned value - max 32 bits */
+        int32_t  lSValue;       /* Stored signed value - max 32 bits */
+        TL_BITS  Bits;          /* Stored bitstring - max 32 bits */
+        TL_ERROR Error;         /* Two part error class/code combo */
+        float    fTime;         /* Interval value for change of time - seconds */
+    } Datum;
+} TL_DATA_REC;
+
+#define TL_T_START_WILD 1 /* Start time is wild carded */
+#define TL_T_STOP_WILD  2 /* Stop Time is wild carded */
+
+#define TL_MAX_ENTRIES 1000 /* Entries per datalog */
+
+/* Structure containing config and status info for a Trend Log */
+
+typedef struct tl_log_info {
+    bool bEnable;               /* Trend log is active when this is true */
+    BACNET_DATE_TIME StartTime; /* BACnet format start time */
+    time_t tStartTime;          /* Local time working copy of start time */
+    BACNET_DATE_TIME StopTime;  /* BACnet format stop time */
+    time_t tStopTime;           /* Local time working copy of stop time */
+    uint8_t  ucTimeFlags;       /* Shorthand info on times */
+    BACNET_DEVICE_OBJECT_PROPERTY_REFERENCE Source; /* Where the data comes from */
+    uint32_t ulLogInterval;     /* Time between entries in seconds */
+    bool bStopWhenFull;         /* Log halts when full if true */
+    uint32_t ulRecordCount;     /* Count of items currently in the buffer */
+    uint32_t ulTotalRecordCount;     /* Count of all items that have ever been inserted into the buffer */
+    BACNET_LOGGING_TYPE LoggingType; /* Polled/cov/triggered */
+    bool bAlignIntervals;            /* If true align to the clock */
+    uint32_t ulIntervalOffset;       /* Offset from start of period for taking reading in seconds */
+    bool bTrigger;                   /* Set to 1 to cause a reading to be taken */
+    int iIndex;                      /* Current insertion point */
+    time_t tLastDataTime;
+} TL_LOG_INFO;
+
+/* 
+ * Data types associated with a BACnet Log Record. We use these for managing the
+ * log buffer but they are also the tag numbers to use when encoding/decoding
+ * the log datum field.
+ */
+
+#define TL_TYPE_STATUS  0
+#define TL_TYPE_BOOL    1
+#define TL_TYPE_REAL    2
+#define TL_TYPE_ENUM    3
+#define TL_TYPE_UNSIGN  4
+#define TL_TYPE_SIGN    5
+#define TL_TYPE_BITS    6
+#define TL_TYPE_NULL    7
+#define TL_TYPE_ERROR   8
+#define TL_TYPE_DELTA   9
+#define TL_TYPE_ANY     10 /* We don't support this particular can of worms! */
+
+
     void Trend_Log_Property_Lists(
         const int **pRequired,
         const int **pOptional,