Emerson 250-5000, Installation And Operation Manual

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Energy Meter Installation and Operation Manual 026-1726 Rev 2
• The RS-485 transceivers are ¼ unit load or less.
• RS-485+ has a 47 kOhm pull up to +5V, and RS-485- has a 47 kOhm pull down to Shield (RS-485 signal ground).
• Wire the RS-485 bus as a daisy chain from device to device, without any stubs. Use a 150 ohm termination resistor
at the end of the bus between the Energy Meter’s + and
-
terminals (not included, or use Emerson MODBUS
termination block P/N 535-2711 ).
• Shield is not internally connected to Earth Ground.
• Connect Shield to Earth Ground somewhere on the RS-485 bus.
• When tightening terminals, ensure that the correct torque is applied: 0.37-0.44 ft·lb (0.5-0.6 N·m).
Figure 6-9
- Energy Meter Wiring