4.Spa Bus - ABB REX 521 Technical Reference Manual, General

1MRS 751108-MUM
4.1.12.4.
Protection Relay
Technical Reference Manual, General
SPA bus
The SPA bus protocol uses an asynchronous serial communication protocol (1 start
bit, 7 data bits + even parity, 1 stopbit). Adjustable parameters are "Baud rate"
(default 9,6 kbps) and "SPA address" (slave number). The communication
parameters for the front and the rear communication ports can be set individually.
The SPA bus protocol is sending events using event mask 1 ("V101" parameter of
each function block). The SPA event buffer stores the first 50 events.
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In the case of longer transmission distance e.g. between MicroSCADA system and
a substation, a following (Fig. 4.1.12.4.-2) system configuration is recommended.
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