KROHNE MFC 010 C Converter - Manual (Page 8)

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MFC010 Interface Manual
3. Electrical Installation
The MFC010 is provided with four electrical terminal connections.
V+ The power supply input terminal.
V- The power supply return path and “Common” for the Modbus interface.
A The inverting (RS485-) terminal for the Modbus interface.
B The non-inverting (RS485+) terminal for the Modbus interface.
These terminals can be accessed in the terminal compartment of the sensor.
3.1 Electrical Input Specifications for the MFC010
NB all voltages, unless otherwise stated, are with reference to the “V-” terminal.
V+ Terminal
Min. Input Voltage 11.4V DC
Max. Input Voltage 12.6V DC
Max. Input Current 200mA DC
A & B *
Min. Input Voltage -7V DC
Max. Input Voltage +11.8V DC
Min. Output Voltage -6V DC
Max. Output Voltage +6V DC
*The M odbus pr otocol r equires t hat t he c ommunications i nterface t o t he MFC010 complies with the
limitations of the EIA/TIA-485 (RS485) specification.
For a standard, non hazardous area, sensor the input impedance of the MFC010 is equivalent to 1/8 of a
standard RS485 load, i.e. an input impedance of >96kΩ, permitting it to be connected to the Modbus bus
in accordance with the Modbus requirements. However, when installed in a Hazardous area the MFC010
requires that suitable barrier devices must be fitted between the MFC010 and the Modbus main bus, see
sections 4.1 & 4.2 for details of suggested barrier devices and c onnection. I f the main Modbus Bus is
configured f or m ultidrop oper ation, a M odbus c ompatible R S485 r epeater i s r equired to connect the
barrier devices to the bus, see section 4.3 for further details.