Electrical connection Proline Promass E 100 Modbus RS485
24 Endress+Hauser
7 Electrical connection
NOTICE
The measuring device does not have an internal circuit breaker.
‣
For this reason, assign the measuring device a switch or power-circuit breaker so that
the power supply line can be easily disconnected from the mains.
‣
Although the measuring device is equipped with a fuse, additional overcurrent
protection (maximum 16 A) should be integrated into the system installation.
7.1 Electrical safety
In accordance with applicable federal/national regulations.
7.2 Connection conditions
7.2.1 Required tools
• For cable entries: Use corresponding tools
• For securing clamp (on aluminum housing): Allen screw3 mm
• For securing screw (for stainless steel housing): open-ended wrench 8 mm
• Wire stripper
• When using stranded cables: crimper for wire end ferrule
7.2.2 Requirements for connecting cable
The connecting cables provided by the customer must fulfill the following requirements.
Permitted temperature range
• The installation guidelines that apply in the country of installation must be observed.
• The cables must be suitable for the minimum and maximum temperatures to be
expected.
Power supply cable (incl. conductor for the inner ground terminal)
Standard installation cable is sufficient.
Signal cable
Modbus RS485
The EIA/TIA-485 standard specifies two types of cable (A and B) for the bus line which
can be used for every transmission rate. Cable type A is recommended.
Cable type A
Characteristic impedance 135 to 165 Ω at a measuring frequency of 3 to 20 MHz
Cable capacitance < 30 pF/m
Wire cross-section
> 0.34 mm
2
(22 AWG)
Cable type Twisted pairs
Loop resistance ≤110 Ω/km
Signal damping Max. 9 dB over the entire length of the cable cross-section
Shield Copper braided shielding or braided shielding with foil shield. When grounding
the cable shield, observe the grounding concept of the plant.
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