Rs485 Connections - GE Multilin MM300 Quick Start Manual

CHAPTER 2: INSTALLATION
NOTE:
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NOTE:
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RS485 connections

MM300 MOTOR MANAGEMENT SYSTEM – QUICKSTART GUIDE
The above drawing applies only to a high-voltage power supply. If a low-voltage (DC)
power supply is used, an appropriate DC voltage source must be used for this power
supply.
.
The full-voltage non-reversing starter type is a full voltage or across-the-line non-reversing
starter.
When a start control is received, the pre-contactor relay (if any) is picked up for the set pre-
contactor time. When the pre-contactor timer times out, relay1 picks up and seals-in,
picking up contactor M, which starts the motor. When a stop control is received, relay1
drops out, contactor M drops out, and the motor stops. The pre-contactor is omitted on
forced starts (for example, UVR Immediate, External Start).
Connect AUX VT to the Control Supply for correct operation of the UV Restart feature and
correct input readings.
Figure 2-12: Typical RS485 connection
Z T (*)
OPTOCOUPLER
DATA
COM
SCADA, PLC, OR
PERSONAL COMPUTER
GROUND THE SHIELD AT THE
SCADA/PLC/COMPUTER ONLY
OR THE MM300 ONLY
(*) TERMINATING IMPEDANCE AT EACH END
(t picall 120 ohms and 1 nF)
One two-wire RS485 port is provided. Up to 32 MM300 IEDs can be daisy-chained together
on a communication channel without exceeding the driver capability. For larger systems,
additional serial channels must be added. Commercially available repeaters can also be
used to add more than 32 relays on a single channel. Suitable cable should have a
characteristic impedance of 120 ohms and total wire length should not exceed 1200
meters (4000 ft.). Commercially available repeaters will allow for transmission distances
greater than 1200 meters.
Voltage differences between remote ends of the communication link are not uncommon.
For this reason, surge protection devices are internally installed across all RS485 terminals.
Internally, an isolated power supply with an optocoupled data interface is used to prevent
noise coupling.
TWISTED PAIR
SHIELD
B1
B2
B3
UP TO 32 MM300
OR OTHER IEDs,
MAXIMUM CABLE
LENGTH OF
Z T (*)
1200 m (4000 ft.)
ELECTRICAL INSTALLATION
MM300 IED
RS485 +
OPTOCOUPLER
RS485 -
DATA
COMMON
IED
RS485 +
RS485 -
COMMON
IED
RS485 +
RS485 -
LAST
COMMON
DEVICE
853745A1.CDR
9