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130 620 300 Rev.C 171116
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INSTALLATION MANUAL
ProSMS 8
6.2
MODBUS typical communication connections
The ProSMS provides duplicate MODBUS interface terminals (GND, A, B). Communication cabling from
the previous device, and cabling to the next device, can be directly connected to these terminals to save
cost (Fig. 6-3).
For more convenient field installation a larger intermediate external communication terminal can be
added in the cabinet (Fig. 6-4). When using an external terminal, cable lengths of less than 1m are
recommended. The cable from the intermediate terminal to the ProSMS does not have to be the same
as the main communication cable and can be of a smaller cross-section,
for example:
0.2mm
2
but still
needs to be RS485 certified twisted pair shielded cable.
The third solution with external terminals is to wire both RS485 connections from ProSMS to the
external terminal (Fig. 6-5) so no Stub forms in the communication bus but care has to be taken to use
the same cross-section and electrical properties cable as it’s used for the main lines between combiner
boxes.
The second solution (Fig. 6-4) is recommended since it provides a good compromise between
connection convenience and reliability.
Fig. 6-3: Direct MODBUS cabling conn
ec�on to Pr
oSMS in combiner box enclosure
CAUTION
VOLTAGE
DANGER
WARNING
NOTICE
Fig. 6-3: Direct MODBUS cabling connection to ProSMS in combiner box enclosure
Summary of Contents for ProSMS 8
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