
4�- OPERATION
The CEM M-RS485 is designed to be used as a RS-485 electrical port for any device in the
CEM family, using the mechanical coupling next to the optical port.
4.1.- OPERATING PRINCIPLE
The CEM M-RS485 is an optional accessory for electrical energy meters from the CEM range
that are mounted on DIN rails.
The CEM M-RS485 provides CEM units with RS-485 communications with the MODBUS
protocol.
Once the unit is coupled to the CEM energy meter (See “3.2.- INSTALLATION”) the LINK LED
turns green to let the user know that the link has been made correctly.
From this point onward, the new CEM energy meter + CEM M-RS485 assembly functions as
a single device.
This assembly operates the same as any standard slave device with a RS-485 bus, responding
to MODBUS requests from the bus's master peripheral.
4.2.- LED INDICATORS
The unit has three indicator LEDs:
POWER
LINK
COMS
Figure 5:CEM M-RS485 indicator LEDs�
POWER LED: Indicates that the unit is connected to a power supply�
LINK LED: Indicates the status of the link with the CEM unit. (Table 3)
11
Instruction Manual
CEM M-RS485
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