MC20-CEI
Doc. N°
MO-0431-ING
Microelettrica Scientifica S.p.A. - Copyright 2009
FW 1080.36.03.X
Date 18.11.2011
Rev.
3
Pag. 22
of 35
11. Serial Communication
11.1 - Main RS485 Serial Communication Port
This port is accessible via the terminals 1-2-3 provided on the relay terminal board.
It is used for connection to a serial bus interfacing up to 31 units with the Central Supervision System (SCADA,
DCS, ecc).
The serial bus is a shielded pair of twisted cables connecting in parallel (Multi Drop) the different units (slaves) by
the relevant terminals.
The physical link is RS485 and the Communication Protocol is MODBUS/RTU / IEC60870-5-103.
The configuration of transmission parameters is selectable.
Baud Rate
:
9600/19200 bps
9600/19200 bps
9600/19200 bps
Start bit
:
1
1
1
Data bit
:
8
8
8
Parity
:
None
Odd
Even
Stop bit
:
1
1
1
Note: any change of this setting becomes valid at the next power on.
Each relay is identified by its programmable address code (NodeAd) and can be called from the P.C.
A dedicated communication software (MSCom) for windows XP/Vista/Win 7 (or later) is available.
Please refer to the MSCom instruction manual for more information.
Maximum length of the serial bus can be up to 200m.
For longer distance and for connection of up to 250 Relays, optical interconnection is recommend.
(please ask Microelettrica for accessories)
