Spa Application Data; Spa Protocol; Supported Spa Data; Reading Of Spa Data - ABB Relion 620 Series Protocol Manual

1MRS757645 B
3.5
3.5.1
3.5.2
3.5.3
620 series
Communication Protocol Manual

SPA application data

SPA protocol

The Modbus protocol includes an internal Modbus ASCII to SPA protocol converter.
The SPA protocol is available as a resident extension to the Modbus ASCII protocol
and it operates only through the asynchronous serial interface. This interface provides
connection to gateway products requiring SPA.
The SPA protocol reuses the settings available for the Modbus ASCII link. The link
characteristics are similar in the SPA protocol and Modbus ASCII protocol standards
(1 start bit, 7 data bits, even parity, 1 stop bit).
The Modbus unit number setting is reused as the SPA slave number. No additional
protocol mode parameter exists. The IED Modbus ASCII link detects the incoming
master messages and automatically adjusts itself according to the protocol. This
switching happens seamlessly, restarting the IED is not required.
The SPA conversion from or to Modbus ASCII is done according to the predefined
rules. The basic principle is that all data available for the Modbus interface is also
available for the SPA protocol. If data is not available through the Modbus interface,
it is not available for the SPA protocol either.

Supported SPA data

The IED supports general SPA data.
• The IED responds with its device type to SPA fiction reading (RF:).
• The IED responds to SPA event reading (RL:) and SPA event backup reading
(RB:).
• SPA time synchronization messages are accepted and the IED real-time clock can
be synchronized from this source. Both WT: and WD: messages are supported.
• The IED accepts the WC:0 acknowledge messages from the master.

Reading of SPA data

SPA data derives directly from the IED Modbus data. All Modbus data in monitoring
direction can be read through Modbus input or holding registers. Modbus registers are
theoretically addressed 1...65535, but in practice the highest available address is
9999.
16-bit wide Modbus registers can contain either one analog value or a set of maximum
16 packed indication bits. In some cases two consecutive Modbus registers have been
defined to contain one 32 bit analog value.
The SPA channel number corresponds to the Modbus register address in the SPA read
messages.
Vendor-specific implementation
Section 3
65