Watlow PM LEGACY PM3 - Page 28

Watlow PM LEGACY
™
Limit Controller • 28 • Chapter 2 Install and Wire
Note:
Do not leave a USB to EIA-485 converter connected to Standard Bus without power (i.e., discon-
necting the USB end from the computer while leaving the converter connected on Standard Bus).
Disturbance on the Standard Bus may occur.
EIA-232/485 Modbus RTU Communications
485 common
485 T-/R-
CB
CA
CC
CB
CA
C5
C3
C2
Slot B or E
485 T+/R+
485 T-/R-
485 T+/R+
232 common
232 (TX) to DB9 pin 2 (RD)
232 (RD) to DB9 pin 3 (TX)
• 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 daisy-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.
• Do not wire to both the EIA-485 and the EIA-232 pins at the same
time.
• Two EIA-485 terminals of T/R are provided to assist in daisy-chain wir-
ing.
• Do not connect more than one PM LEGACY™ Limit controller on an
EIA-232 network.
• Maximum number of PM LEGACY™ Limit controllers on a Modbus
network is 247.
• Maximum EIA-232 network length: 15 meters (50 feet)
• Maximum EIA-485 network length: 1,200 meters (4,000 feet)
• 1/8th unit load on EIA-485 bus.
• Communications instance 2
Slot B
PM6[L,M] _ _J - [F,2] _ _ _ G_ _
Modbus-IDA
Terminal
EIA/TIA-485
Name
Watlow Termi-
nal Label
Function
DO A CA or CD T-/R-
D1 B CB or CE T+/R+
common common CC or CF common
EtherNet/IP™, PCCC and Modbus
®
TCP Communications