Microset Field Service mode custom codes
VLCs enable you to set up custom field service codes for the Microset. Using
this feature, you can display and change the value of AI (read-only), BI (readonly),
AV, BV, AO, and BO objects from the BACtalk Microset. You can set up
to 26 field service mode codes.
In Field Service mode, a series of two-character codes correspond to each object.
You select the objects to be displayed and choose the codes that identify them
using the Microset Field Service Mode Setup screen (F6 Microset Field Service
Mode Control Table from the DDC Header menu).
Entry Identifies the entry and can’t be edited. In Field Service mode, entry 0
appears first, entry 25 appears last.
Display Code The two-digit code to be displayed at the Microset. Limited to
acceptable characters and must be two characters. Press F5 to view the list of
acceptable characters or use the following reference. Position the cursor in this
field, press Enter, and then type acceptable characters.
Point ID Defines the VLC data point whose value will be associated with the
display code. AI, BI, AO, BO, AV, and BV are acceptable point types. Position
the cursor in this field, press Enter, and then type an acceptable point type. Press
Enter again and type the point’s instance (for AI 1, type 1, for example). Make
sure the point you reference actually exists in the VLC.
Table 48 Acceptable Microset Field Service mode characters
0 1 2
3 4 5
6 7 8
a.The characters 9 and g are virtually indistinguishable on the Microset display.
c C d
E F g
h H i
J L n
o p r
u U y
Programmer’s Guide and Reference | BACtalk Systems
156 © Novar Controls Corporation. All Rights Reserved. LTBT-TM-PRGRMR Rev. 0008
Writable Determines whether the value will be writable from the Microset
(YES) or read only (NO). Position the cursor in the field and press Enter to
toggle the value. AIs and BIs are not writable.
Decimal Determines whether the Microset will show the value with a decimal
(YES) or without one (NO). Position the cursor in this field and press Enter to
toggle the value.
CAUTION The BACtalk Microset displays OFF values as 0 and ON values as
.1. You must set the Decimal field to YES to view or change binary values at the
Positive only Determines whether only positive values can be displayed (YES)
or negative values as well (NO). Position the cursor in this field and press Enter
to toggle the value.
Setting parameters for a VAV airflow sensor
VAV controllers have a special screen in the VLC DDC program for setting up
airflow sensor parameters. In this configuration screen, you specify a box size, a
calibration factor, the point below which airflow should read zero (zero cutoff),
and the values of AI-8 and AI-10 (for dual duct VLCs), or AI-10 (for single duct
Note You can also adjust the values for the hot duct and cold duct calibration
factors from the BACtalk Microset using the Microset Airflow Calibration
This is a one-time setup you perform for each VAV VLC; the setup is stored in
the VLC independently of DDC or header information. This configuration
affects the values that represent airflow for VAV VLCs.
Note The program units setting (English or metric) in the Analog Input Setup
screen (see “AI setup” on page 152) determines whether AIs report airflow in
cfm or lps, and whether temperatures are reported in degrees F or C.
! To set up airflow parameters for a VAV VLC
1. Make sure you select the Device ID of the VLC you want to work with
in the Configuration screen. Also, choose F2 Read File to retrieve the
existing setup data from the VLC so you do not inadvertently overwrite
an existing setup.
2. From the VLC DDC Main menu, choose F1 Configure.
3. From the Configuration menu, choose F3 VAV Flow Sensor.
The VAV Flow Sensor Setup screen appears with fields for entering a
box size, calibration factor, and velocity zero cutoff for both the cold
duct and the hot duct. For single-duct VAV controllers (SD), only the
cold duct information is used.
4. Position the cursor in the field you want to edit, press Enter, and then set
parameters according to the following guidelines.
Chapter 9 | DDC header file setups in VLC DDC
© Novar Controls Corporation. All Rights Reserved. LTBT-TM-PRGRMR Rev. 0008 157
Box diameter The box diameter of the VAV box to be controlled by this VLC.
Enter this value in inches or centimeters as appropriate for English or metric
setup in the AI Setup screen (see “AI setup” on page 152). Obtain box diameter
data from the VAV box manufacturer. The box diameter represents the round
duct equivalent diameter of the duct where the pressure pickup is located.
Calibration factor Adjusts the VLC airflow readings to match the specific VAV
box, airflow pickup, and conditions of an installation. Increasing the value of the
calibration factor will increase the value of the corresponding airflow (AI-8 for
hot duct flow, if applicable; AI-10 for cold duct flow).
The calibration factor for each duct should be adjusted until the corresponding
airflow matches the airflow measured using a balancing hood. The default value
for the calibration factor, 1.00, accounts for no pressure loss in the tubes.
Increase the calibration factor to compensate for tube loss.
Velocity zero cutoff This value is entered in percent of full airflow (0-100).
Airflows lower than the cutoff are reported as zero. This feature eliminates nonzero
airflow readings due to ambient fluctuations when the main fan is off.
! To send data to the VLC
• When you finish, press F1 to send the VAV airflow setup
information to the VLC.