Table 4: Communication Bus and Supply Power Terminal Blocks, Functions, Ratings, Requirements, and
Cables
Recommended Cable Type
1
Function, Electrical Ratings/Requirements
Terminal Labels
Terminal
Block/Port Label
24 AWG 3-pair CAT 3 Cable
<30.5 m (100 ft)
RJ-12 6-Position Modular Connector provides:
SA Bus Communications
SA Bus Signal Reference and 15 VDC Common
15 VDC Power for devices on the SA Bus
SENSOR
SENSOR
2
(SA Bus Port)
0.8 mm to 1.0 mm
(20 to 18 AWG) 2-wire
24 VAC Power Supply - Hot
Supplies 20–30 VAC (Nominal 24 VAC)
HOT
24~
24 VAC Power Supply Common
(Isolated from
all other Common terminals on controller)
COM
1
See
Table 2
to determine wire size and cable lengths for cables other than the recommended cables.
2
The SA Bus and FC Bus wiring recommendations in this table are for MS/TP bus communications at 38.4k baud. For more
information, refer to the
MS/TP Communications Bus Technical Bulletin (LIT-12011034)
.
Setup and Adjustments
Important:
Electrostatic discharge can damage
controller components. Use proper
electrostatic discharge precautions during
installation, setup, and servicing to avoid
damaging the controller.
Setting the Device Address
Metasys
field controllers are master devices on BACnet
MS/TP (SA or FC) buses. Before operating controllers
on a bus, you
must
set a valid and unique device address
for each controller on the bus.
You set a controller's device address by setting the
positions of the switches on the Device Address DIP
switch block at the top of the controller (
Figure 2
). Valid
addresses for these controllers are device addresses 4
through 127.
The DIP switch block (
Figure 8
) has eight switches
numbered 128, 64, 32, 16, 8, 4, 2, and 1. Switches 64
through 1 are device address switches. Switch 128 is a
mode switch that enables a field controller to operate on
a ZFR1800 Series Wireless Field Bus. Switch 128 must
be set to off for all hard-wired SA and FC Bus
applications.
Figure 8: Device Address Switches Set to 21
Note: Metasys
field controllers ship with switch 128 ON
and the remaining address switches off. This
renders the controllers wired slave devices, which
do not operate on MS/TP buses, but do not
interfere with bus operation. Set a valid and
unique device address on the controller before
applying power to the controller on the bus.
To set the device addresses on a VMA controller:
1. Set all of the switches on the controller’s device
address DIP switch block (128 through 1) to off.
2. Set one or more of the seven address switches (64
through 1) to ON, so that the sum of the switch
numbers set to ON equals the intended device
address. See
Table 5
for valid controller addresses.
Set the highest number switch that is less than or
equal to the intended device address to ON. Then
continue setting lower numbered switches until the
total equals the intended address. For example, if the
intended device address is 21, set switch 16 to ON
first, then set switch 4 ON, followed by switch 1
(16+4+1= 21). See
Figure 8
.
Note:
Do not connect a field controller with switch
128 set to
ON
to an active (hard-wired) SA or
FC Bus. When a controller with switch 128 set
to
ON
and a device address from 4 to 127 is
connected to a wired field bus, the entire field
bus is rendered inoperable until the controller
is disconnected or switch 128 is set to
OFF
.
3. Set a unique and sequential device address for each
of the controllers connected on the SA or FC Bus
starting with device address 4.
14
VMA1610 and VMA1620 Variable Air Volume Controllers Installation Instructions
