Schweitzer Engineering Laboratories SEL-387-0, Instruction Manual

Page: 535 / 568

F.7
Date Code 20050919
Instruction Manual SEL-387-0, -5, -6 Relay
Unsolicited SER Protocol
Functions and Function Codes
Notes
Once the relay receives an acknowledge with response code 00 from the
master, it will clear the settings changed bit (bit 1) in its status byte, if that bit
is asserted, and it will clear the settings changed bit in fast meter, if that bit is
asserted.
An element index of 0xFE indicates that the SER record is due to power up.
An element index of 0xFF indicates that the SER record is due to setting
change. An element index of 0xFD indicates that the element identified in this
SER record is no longer in the SER trigger settings.
When the relay sends an SER message packet, it will put a sequential number
(0, 1, 2, 3, 0, 1, ...) into the response number. If the relay does not receive an
acknowledge from the master before approximately 500 ms, the relay will
resend the same message packet with the same response number until it
receives an acknowledge message with that response number. For the next
SER message, the relay will increment the response number (it will wrap
around to zero from three).
A single SER message packet from the relay can have a maximum of 32
records and the data may span a time period of no more than 16 seconds. The
master can limit the number of records in a packet with the third byte of
function code data in the “Enable Unsolicited Data Transfer” message
(function code 01). The relay can generate an SER packet with less than the
requested number of records, if the record time stamps span more than 16
seconds.
The relay always requests acknowledgment in unsolicited SER messages
(LSB of the status byte is set).
Unsolicited SER messages can be enabled on multiple ports simultaneously.