Installation; Biasing And Termination - Johnson Controls EMCOMMS Series Installation Instructions

INSTALLATION

MOUNTING
The EMCOMMS meter features four mounting options for
convenience: rare earth magnets, mounting tabs, horizontal
DIN rail and vertical DIN rail.
Magnetic mount--no drilling!
Slide On
DIN Rail (vertical)
Figure 3: EMCOMMS Meter Mounting Options
WIRING
Line Status
LED Status LED
EMCOMMS
Setup Bu�on
Serial Number
511Ω Pullup bias resistor
120Ω Bus termina�on resistor
511Ω Pulldown bias resistor
1
One side of transformer secondary is connected to signal common.
Dedicated transformer is recommended.
Figure 4: EMCOMMS Meter Wiring
NETWORK SUPPORT
The EMCOMMS meter supports use on both BACnet and
Modbus networks. The default settings on the meter includes
auto-detection of protocol type, device address, serial format
and baud rate. Each meter ships with a default Modbus address.
This process is further detailed in Network Connectivity (page 3).
RS485 WIRING BEST PRACTICES
Use of appropriate shielded twisted pair wire (14-26 AWG) is
recommended, per protocol specifications. Total wiring runs
should not exceed 4000 feet, with a maximum of 128 devices
(BACnet) or 32 devices (Modbus) in a single daisy chain.
DAISY CHAIN WIRING EXAMPLE
S
511Ω Pullup bias resistor
120Ω Bus termina�on resistor
511Ω Pulldown bias resistor
Figure 5: Daisy Chain Wiring
Snap-in mounting tabs
Slide On
DIN Rail (horizontal)
Power
12-30VDC/24VAC
Device
Ground
Pulse Input 1
Pulse Input Ground
RS485
Status LED
Pulse Input 2
RS-485 +
Isolated Ground/Shield
RS-485 -
Termination
on
o
EOL 120 Resistor

BIASING AND TERMINATION

Use the jumpers to select the 120 ohm EOL resistor if EMCOMMS
meter is the last device in your network. If the meter is being
installed within a network of other existing RS485 devices, it
may be necessary to use the 511 ohm biasing resistors based on
your network or hardware requirments. See Figure 4. EMCOMMS
Meter Wiring for locations of jumpers and values.
PULSE INPUT WIRING
The EMCOMMS meter is capable of accepting dry pulse
(outputs) from other devices and meters (water, gas, steam,
etc). It will count the pulses and report them in BACnet Objects
and/or Modbus registers. These discrete registers reported as
Pulse 1 and Pulse 2 can then be 'mapped' in your controller or
software to the engineering unit being monitored i.e. GPM,
BTU, CFM, etc.
When connecting 3rd party outputs to the EMCOMMS meter,
it is important to ensure the pulse rating of the outputs do not
exceed rating of the meter in Specifications (page 5).
2
1
Figure 6: Pulse Input Wiring
CVT CONNECTION
The EMCOMMS meter is compatible with all Johnson Controls
ROG Series Current/Voltage Transducers (CVTs). Each CVT will
self-configure to the meter. The meter can accomodate the
connection of up to 3 CVTs. The CVTs can be from a single-phase,
poly-phase or three-phase system; or up to three independent
single-phase loads with mixed amperage and voltage ratings.
TYPICAL 3Ø WIRING 90 to 600VAC
LOAD
L1 L2 L3
R S T
A B C
Data cable
Figure 7: EMCOMMS Meter and CVT Connections
EMCOMMS Series Meter - Installation Instructions
1
Device local ground

Secondary Device
Pulse Output
L1 L2 L3
R S T
Color
N
White
2