Wiring
Deactivate the 24 Vac/dc power supply until all connections
are made to the device to prevent electrical shock or
equipment damage. Follow proper electrostatic discharge
(ESD) handling procedures when installing the device or
equipment damage may occur. Use 22 AWG shielded wiring
for all connections and do not locate the device wires in the
same conduit with wiring used to supply inductive loads
such as motors. Make all connections in accordance with
national and local codes.
Connect the 24 Vac/dc power supply to the terminals
labeled PWR (power) and COM (common) as shown in
Figure 6. This device has a half-wave type power supply so
use caution when wiring multiple devices so that the circuit
ground point is the same on all devices and the controller.
Use caution if 24 Vac power is used and one side of the
transformer is earth-grounded. In general, the transformer
should NOT be connected to earth ground when using
devices with RS-485 network connections. The device is
reverse voltage protected and will not operate if connected
backwards.
Connect the RS-485 network with twisted shielded pair to
the terminals marked A-, B+ and SHLD (shield) as shown in
Figure 6. The positive wire connects to B(+) and the
negative wire connects to A(-) and the cable shield must be
Greystone Energy Systems, Inc. 150 English Drive, Moncton, NB E1E 4G7 Canada Tel: +1-506-853-3057 Tollfree (North America): +1-800-561-5611 Fax: +1-506-853-6014
Email: [email protected] Web: www.greystoneenergy.com
0001342
B+
A-
SHLD
PWR
COM
EOL
2
4
16
32
1
8
64
BUS ADDRESS
0001342
B+
A-
SHLD
PWR
COM
EOL
2
4
16
32
1
8
64
BUS ADDRESS
0001342
B+
A-
SHLD
PWR
COM
EOL
2
4
16
32
1
8
64
BUS ADDRESS
B+
A-
Shield
24 Vdc
Common
connected to the SHLD terminal on each device. If the device is installed at either end of the network, an end-of-line (EOL)
termination resistor (121 ohm) should be installed in parallel to the A(-) and B(+) terminals. This device includes a network
termination jumper and will connect the resistor correctly on the pcb. Simply move the pcb jumper to the EOL position and
no external resistor is required as shown in Figure 7. The ground wire of the shielded pair should be connected to earth
ground at the end of the network and the master is not grounded. Do not run bus wiring in the same conduit as line voltage
wiring.
A network segment is a single shielded wire loop run between several devices (nodes) in a daisy chain configuration. The total
segment length should be less than 4000 feet (1220 meters) and the maximum number of nodes on one segment is 127.
Nodes are any device connected to the loop and include controllers, repeaters and sensors such as the RH/T Sensor but does
not include the EOL terminators. To install more devices, or to increase the network length, repeaters will be required for
proper communication. The maximum daisy chain length (segment) depends on transmission speed (baud rate), wire size
and number of nodes. If communication is slow or unreliable, it may be necessary to wire two daisy chains to the controller
with a repeater for each segment.
0001342
B+
A-
SHLD
PWR
COM
EOL
2
1
BUS ADDRESS
0001342
B+
A-
SHLD
PWR
COM
EOL
2
1
BUS ADDRESS
0001342
B+
A-
SHLD
PWR
COM
EOL
2
1
BUS ADDRESS
B+
A-
Shield
External 24 Vdc
Power Supply or
24 Vac Transformer
Common
Modbus Master
Modbus Master
Building Controller
0001342
B+
A-
SHLD
PWR
COM
EOL
2
4
16
32
1
8
64
BUS ADDRESS
EOL
EOL
OFF
ON
Set EOL
Jumper
Figure 5
Figure 6
Figure 7
Building Controller
Device 1
Device 2
Device 3
Device 1
Device 2
Device 3
Connect Shield One End Only
Connect Shield One End Only
0001338
B+
A-
SHLD
PWR
COM
EOL
2
4
16
32
1
8
64
BUS ADDRESS
128
