Watlow PM LEGACY
™
Limit Controller
•
27
•
Chapter 2 Install and Wire
Quencharc Wiring Example
I
n this example the Quencharc circuit (Watlow part#
0804-0147-0000) is used to protect PM internal circuitry
from the counter electromagnetic force from the induc-
tive user load when de-energized. It is recommended
that this or an equivalent Quencharc be used when con-
necting inductive loads to PM outputs.
Quencharc
User Load
N
L_
K_
Standard Bus EIA-485 Communications
Standard Bus
EIA-485
T-/R-
common
98
99
CF
CD
CE
B5
D6
D5
Slot C
T+/R+
• Wire T-/R- to the A terminal of the EIA-485 port.
• Wire T+/R+ to the B terminal of the EIA-485 port.
• Wire common to the common terminal of the EIA-485 port.
• Do not route network wires with power wires. Connect network wires in dai-
sy-chain fashion when connecting multiple devices in a network.
• Do not connect more than 16 PM LEGACY™ Limit controllers on a network.
• Maximum network length: 1,200 meters (4,000 feet)
• 1/8th unit load on EIA-485 bus
PM[3,6][L,M] _ _J - [A,B] _ _ _ G_ _
* All models include Standard Bus communications (instance 1)
Note:
Do not leave a USB to EIA-485 converter connected to Standard Bus without power (i.e.,
disconnecting the USB end from the computer while leaving the converter connected on
Standard Bus). Disturbance on the Standard Bus may occur.
Modbus RTU or Standard Bus EIA-485 Communications
Modbus RTU or
Standard Bus EIA-485
T-/R-
common
98
99
CC
CA
CB
B5
D6
D5
Slot C
T+/R+
• Wire T-/R- to the A terminal of the EIA-485 port.
• Wire T+/R+ to the B terminal of the EIA-485 port.
• Wire common to the common terminal of the EIA-485 port.
• Do not route network wires with power wires. Connect network wires in dai-
sy-chain fashion when connecting multiple devices in a network.
• A termination resistor may be required. Place a 120 Ω resistor across T+/R+
and T-/R- of last controller on network.
• Only one protocol per port is available at a time: either Modbus RTU or Stan-
dard Bus.
• Do not connect more than 16 PM LEGACY™ Limit controllers on a Standard
Bus network.
• Maximum number of PM LEGACY™ Limit controllers on a Modbus network is
247.
• Maximum network length: 1,200 meters (4,000 feet)
• 1/8th unit load on EIA-485 bus.
• Communications instance 1
PM[3,6][L,M] _ _J - [E,1] _ _ _ G_ _
Содержание PM LEGACY PM3
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