NuAire B 07T/CO Series, Installation Manual

Page: 27 / 52

27
30. 07. 20. Document Number 671760 Nuaire |
Western Industrial Estate
|
Caerphilly
|
CF83 1NA
| nuaire.co.uk
BPS V-CO
Installation Manual
8.30 Typical Basic Operation
• Enable the unit using the MSV “Enable” object. The fan runs at min
speed.
• Increase the fan speeds using the AV “Fan Speed Demand” 0-100%
(0% = Min Commissioned Speed, 100%= Max Commissioned
Speed).
• Adjust setpoint using the AV “Software Setpoint”.
8.31 Writing Directly To Outputs
• It is not recommended to write directly to outputs since the
internal logic of the control will be bypassed and some features
will not function. The unit may also start without an enable signal.
• However, if this is required for test purposes (or otherwise),
priority level 8 must be used.
• The internal control logic writes at priority level 16 so any data
written to the outputs at this level is at risk of being overwritten.
• These values must be relinquished or nulled once used, otherwise
the outputs will be locked at that value, even if the value is “0”.
8.32 Priority Array Storage
• Priority levels 8 & 16 are stored in the controller following a power
cycle. All other levels are reset to null.
• Level 16 is not to be used for controller outputs since it will be
overridden by the internal logic during operation.
8.33 Devices
A BACnet network can consist of a number of "device objects". Each
device is given a unique "Device Instance Number". A typical example
of a device is a controller or BACnet compatible LCD. EcoSmart
Connect controllers are assigned a random device instance number at
the factory and do not need to be changed. The instance number range
is 1 - 4,194,303 (2
22 ).
EcoSmart Connect controllers use a MSTP network for
communication and are assigned a MSTP address (4 -127) by the
dip switch located on the front of the controller. The MSTP address
must not be confused with the Device Instance Number.
Most network browsers can identify a device by the Device Instance
Number or the MSTP address.
8.34 Objects
In BACnet, information is stored within devices as a number of ‘virtual’
objects. Some examples of these are Fresh Air Temperature, Extract Fan
Speed, CO2 Target, etc.
Each object has a number of properties but the most important are
shown in the table below. The maximum number of objects in a device
is 4,194,303 (2
22
) of each type.
Object Name The name of the object. E.g. Setpoint
Object Instance
Number
A unique number which represents the object within
the device. E.g. 12544
Object Type The type of object. E.g. Analogue Variable (AV)
Description A short description of the object. E.g. The room
setpoint
Present Value The current value of the object. E.g. 20
Units The units of the present value. E.g. °C
8.35 Object Types
A list of some typical object types is shown below.
AI Analogue
Input
An analogue object which is a physical input to a device.
AO Analogue
Output
An analogue object which is a physical output from a
device.
AV Analogue
Variable
An analogue object which exists within a device.
BI Binary
Input
A true/false object which is a physical input to a device.
BO Binary
Ouput
A true/false object which is a physical output from a
device.
BV Binary
Variable
A true/false object which exists within a device.
MSV Multi-
State
Variable
This is an enumerated object which can have a number
of states, each represented by a number. This is similar
to a dropdown menu in windows forms. The State_Text
property is an array containing the text for each value.
Some browsers may not be able to read the text values
so both are provided in this manual. E.g. 1=Off, 2=Low,
3=High, 4=Auto
SCH Schedule
Object
This is a special object with the ability to have a
changing value depending on the time of date or day of
the week.
8.36 Writing Of Values (Priority Array)
Any device on the BACnet network has the ability to write values to
other device objects.
To resolve conflicts, BACnet uses a 16 position priority array to work
out who gets priority. Any request it change the present value is stored
in the priority array at the priority level of the received request. The
object then chooses the highest priority value to become the present
value. Examples of priority array decision making are shown below.
Case 1
Priority 1 null
Priority 2 null
Priority 3 null
Priority 4 null
Priority 5 null
Priority 6 null
Priority 7 null
Priority 8 null
Priority 9 null
Priority 10 null
Priority 11 null
Priority 12 null
Priority 13 null
Priority 14 null
Priority 15 null
Priority 16 null
Relinquish
Default 0
Present
Value
0
Case 2
Priority 1 null
Priority 2 null
Priority 3 null
Priority 4 null
Priority 5 null
Priority 6 null
Priority 7 null
Priority 8 null
Priority 9 null
Priority 10 null
Priority 11 null
Priority 12 null
Priority 13 null
Priority 14 null
Priority 15 null
Priority 16 5
Relinquish
Default 0
Present
Value
5
Case 3
Priority 1 null
Priority 2 null
Priority 3 null
Priority 4 null
Priority 5 null
Priority 6 null
Priority 7 null
Priority 8 null
Priority 9 7
Priority 10 null
Priority 11 null
Priority 12 null
Priority 13 null
Priority 14 null
Priority 15 null
Priority 16 5
Relinquish
Default 0
Present
Value
7
Case 4
Priority 1 null
Priority 2 null
Priority 3 null
Priority 4 null
Priority 5 null
Priority 6 null
Priority 7 null
Priority 8 null
Priority 9 7
Priority 10 null
Priority 11 null
Priority 12 null
Priority 13 null
Priority 14 null
Priority 15 null
Priority 16 0
Relinquish
Default 0
Present
Value
7
Case 4
Priority 1 null
Priority 2 null
Priority 3 null
Priority 4 null
Priority 5 null
Priority 6 null
Priority 7 null
Priority 8 null
Priority 9 null
Priority 10 null
Priority 11 null
Priority 12 null
Priority 13 null
Priority 14 null
Priority 15 null
Priority 16 0
Relinquish
Default 0
Present
Value
0
• Case 1 - The object looks down the list until it gets to the first
non-null value. In this case, all priority levels are empty so the
(relinquish) default value of 0 is used as the present value.
• Case 2 - Priority 16 is now 5 so the present value becomes 5.
• Case 3 - Priority 9 is now 7. Priority 9 overrules priority 16 so the
present value becomes 7. Note that priority 16 is still calling for 5
but it is being ignored.
• Case 4 - Priority 16 is changed to 0 but this has no effect on the
present value. It is still at 7 because of priority 9.
• Case 5 - Priority 9 is relinquished back to null. This allows priority
16 to take priority again and the present value becomes 0.