13
Controller Network (CNET) overview
PRC-E Series Instruction Manual
MN014003EN August 2015 www.eaton.com
RS-485 (CNET) network
Controllers are connected to a PRC RS-485 network
using the RS-485 connector located in the low voltage
compartment. PRC1000E, PRC1500E, and PRC2000E
controllers include the CNET communications module on
the controller (not available on the PRC750E controller).
See
Figure 20
.
Figure 20 . PRC RS-485 CNET Connection
Pow-R-Command RS-485 network uses a two-wire,
half-duplex network in a daisy-chained architecture.
The connector provided in the controller low voltage
compartment is for connecting the network in and out
cables. The network operates independently of each
controller, meaning that a controller can be powered down
and the network will remain intact and operational.
Following are some general guidelines for installing the
Pow-R-Command RS-485 controller network:
●
●
Maximum of 120 controllers total
●
●
Each controller configured with a unique network address
●
●
Only BELDEN 3105A or equivalent cable should be used
●
●
Maximum overall length of the RS-485 network should
not exceed 4000 feet. If this limit is exceeded, a repeater
may be required
●
●
Surge protection is recommended for networks in noisy
environments (B&B model # 485HESP or equivalent)
●
●
Fiber-optic cable is recommended for outdoor,
underground, or between-structure applications
●
●
Uniform network polarity must be maintained
All controllers in the system must be connected in a daisy
chain; loops, stars, and stubs are not allowed.
The end of the RS-485 network requires a 120 ohm
end-of-line (EOL) termination. The CNET communications
module provides a jumper for applying the terminating
EOL resistor in the controller. By default, the jumper is not
connected. To add the resistor, place the jumper across the
5th set of posts marked with a “T”. See
Figure 21
controller
network jumpers.
Figure 21 . CNET Module
One end of the cable shield must be connected to
the ground.
otee:
N
The shield should only be connected to a service
ground at one location to prevent a ground loop
or common mode voltages from disrupting
communications or cause damage to the
controller circuitry.
No network cable splices are allowed. The RS-485 controller
network is a low-power application and splices can be
detrimental to the performance and reliability of the network.
Controller network access is accomplished by installing
an Ethernet Interface Module between the PRC controller
network and personal computer. Network access requires
the personal computer to be loaded with Pow-R-Command
Lighting Optimization Software (PRCLOS).
Ethernet Interface Module
The Ethernet Interface Module (EIM) allows access to
the PRC controller network when using a PC connected
directly to the EIM Ethernet port or connected on a facility’s
Ethernet network. See
Figure 22
. These same messages
can optionally be tunneled across the Ethernet, providing
access to the entire PRC controller network.
Figure 22 . PRC Ethernet Interface Module (EIM)
(Part # 926C160G04)
RS-485
Controller
Network
Connector
RS-485
Comm.
Board
1st and 2nd row—Weak or Low
Bias jumper (Connected)
3rd and 4th row—Strong or
High Bias jumpers
5th row—Terminating Resistor
(Disconnected Position)