L.6
SEL-351A Relay Instruction Manual Date Code 20080213
SEL Synchrophasors
Protocol Operation
In the SEL Fast Message format, the synchrophasor processor must request a
particular data message period, which is embedded in the enable message. If
the requested message period can be supported, the SEL-351A will
acknowledge the request (if an acknowledgement was requested) and begin
transmitting synchrophasors. If the requested message period is not permitted,
the SEL-351A will respond with a bad data message (if an acknowledge was
requested), and will not transmit any synchrophasor data. Table L.4 lists the
permissible data message periods that can be requested by the enable
message. Note that each Fast Message is transmitted at a fixed time after the
beginning of each minute.
The SEL-351A will only transmit synchrophasor messages over serial ports
that have setting PROTO = SEL. The connected device will typically be a
synchrophasor processor or a communications processor, such as the
SEL-2032. The connected device controls the PMCU functions of the
SEL-351A with SEL Fast Message commands, including commands to start
and stop synchrophasor data transmission.
Table L.2 Unsolicited Fast Message Enable Packet
Field Description Hex Data
Header Synchrophasor Fast Message A546
Frame Size 18 bytes 12
Routing Must be 0000000000 for this application 0000000000
Status Byte YY = 00 acknowledge is not requested
YY = 01 acknowledge is requested
YY
Function Code 01h Enable unsolicited write messages 01
Sequence C0 for single frame message.
Maximum frame size 255 bytes
C0
Response Number XX = 00, 01, 02, 03 XX
Application 20h Synchrophasor 20
Message Period Data message period nnnn
a
a
See Ta b le L . 4 for permissible data message period values.
Check Word 2-byte CRC-16 check code for message XXXX
Table L.3 Unsolicited Fast Message Disable Packet
Field Description Hex Data
Header Synchrophasor Fast Message A546
Frame Size 16 bytes 10
Routing Must be 0000000000 for this application 0000000000
Status Byte YY = 00 acknowledge is not requested
YY = 01 acknowledge is requested
YY
Function Code 02h Disable unsolicited write messages 02
Sequence C0 for single frame message.
Maximum frame size 255 bytes
C0
Response Number XX = 00, 01, 02, 03 XX
Application 20h Synchrophasor 20
Check Word 2-byte CRC-16 check code for message XXXX
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