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VCCX2 Controller Technical Guide
Trend Log Bit String Decoding
Bit String values allow the manipulation of binary data in useful
ways. For instance, a single trend log item may need to represent
multiple simultaneous true conditions. An example would be a
trend log item indicating what binary inputs are currently active,
what relays are currently active, or what alarms are currently
active. A single bit string value can be decoded to determine
which multiple conditions might be simultaneously true. This
section is not intended to be a full explanation of how bit strings
work, but just to explain how to decode the VCCX2 trend log
items that are indicated as being bit string values.
Example
Binary Inputs Bit String Values
0 = No Binary Inputs Active
1 = Fan Proving
2 = Dirty Filter
4 = Hood On/Off
8 = Remote Occupied
16 = Remote Cooling
32 = Remote Heating
64 = Remote Dehumidification
128 = Emergency Shutdown
If the trend log bit string value was 22 for Binary Inputs, you first
identify the highest value shown above that can be subtracted
from 22. That would be 16 (Remote Cooling). So, the Remote
Cooling binary input is currently active. From the remainder of
6 (22 - 16 = 6) you then subtract out the next highest possible
number. That would be 4 = Hood On/Off. So, the Hood On/Off
binary input is also currently active. From the remainder of 2
(6 – 4 = 2) you subtract out the next highest possible number
which is 2 = Dirty Filter. So, the Dirty Filter binary input is also
currently active. There is no remainder (2 – 2 = 0), so there are
no more inputs that are active. From the one value of 22 you are
able to determine that three binary inputs were active when that
trend item was recorded.
With a value of 86, you would have started with 64 = Remote
Dehumidification. This would have left a remainder of 22 (86 –
64 = 22) and you would then continue on to get the same three
additional binary inputs in the previous paragraph.
With any trend log value that is designated to be a bit string value
you simply identify from the trend log section in this technical
guide what the bit string values are for each status condition and
perform the same calculation.
The table that follows provides the Bits, values and descriptions
for the various points on the VCCX2 Controller and associated
modules.
RSMZ VFD Status Decoding
For the RSMZ VFD status, instead of just one set of bit string
values, there are two. The trend log bit string value represents
the values in the BIT=1 column. All other values not represented
in the trend log bit string are then active in the BIT=0 column.
Example
If the trend log bit string was 5, then the following
status would be true
0 = Timer Okay
0 = Torque Okay
0 = Voltage Okay
0 = Drive Okay
0 = No Operation
0 = Out of Frequency Limit
0 = Local Operation
0 = Speed Not Equal Reference
0 = No Warning
0 = No Error
0 = No Error
1 = Enable (Bit Value = 4)
0 = Drive Not Ready
1 = Control Ready (Bit Value = 1)
SEQUENCE OF OPERATIONS
Trend Log Bit String Decoding
