Siemens SITRANS MASS 2100 Compact Operating Instructions page 34

Connecting
4.2 Connecting MASS 2100/FC300
12.Assemble and tighten the cable gland.
13.Remove the O-ring from lid.
14.Reinstate the lid and screw in until the mechanical stop. Wind back the lid by one turn.
15.Mount the O-ring by pulling it over the lid and tighten the lid until you feel friction from the O-
ring on both sides. Wind the lid by one quarter of a turn to seal on the O-ring.
16.Reinstate and tighten the lid lock screw.
Unprotected cable ends
Risk of explosion through unprotected cable ends in hazardous areas.
● Protect unused cable ends in accordance with IEC/EN 60079-14.
It is important to terminate the Modbus RS-485 line correctly at the start and end of the bus
segment. Impedance mismatch results in reflections on the line which can cause faulty
communication transmission.
If the device is at the end of the bus segment, it is recommended to terminate the device. The
following table shows the relation between the DIP switch settings and the permissible
communication interface set-ups.
Note
End Of Line (EOL) termination
The FCT010 EOL termination DIP switch is default set to EOL non-active. If the installation
requires active termination resistors, the DIP switches should be set to the EOL Active state.
Hazardous areas
Only change the DIP switches in hazardous areas when the device is deenergized.
Location of DIP switch
The DIP switch is located in the electronic as shown below.
FW4
34
WARNING
CAUTION
FW3 (before 07/2018)
SITRANS MASS 2100 & FC300 (FCT010)
Compact Operating Instructions, 05/2020, A5E40504094-AB