7.12
SEL-751 Relay Instruction Manual Date Code 20170927
Communications
Communications Protocols
SEL Fast Message
This protocol uses binary messages to receive/transmit data from/to an SEL
communications processor. The protocol is described in Appendix C: SEL
Communications Processors.
SEL Fast SER
This protocol is used to receive binary Sequential Events Record unsolicited
responses. The protocol is described in Appendix C: SEL Communications
Processors.
SEL Event Messenger
This is an SEL ASCII protocol with 8 data bits, no parity, and 1 stop bit for
transmitting data to the SEL-3010 Event Messenger. You can change only the
communications speed to match the settings in the SEL-3010.
Other Supported
Protocols
MIRRORED BITS Protocol
The SEL-751 supports two MIRRORED BITS communications channels,
designated A and B. Within each M
IRRORED BITS communications message
for a given channel (A or B), there are eight logical data channels (1–8). You
can, for example, set MBA on Port 3 of the base unit and MBB on Port 4A of
the optional communications card. Attempting to set the PROTO setting to
MBA, MB8A, or MBTA when Channel A is already assigned to another port
(or MBB, MB8B, or MBTB when Channel B is already assigned on another
port) results in the following error message:
This Mirrored Bits channel
is assigned to another port.
After displaying the error message, the
device returns to the PROTO setting for reentry.
C37.118 Protocol
The SEL-751 provides C37.118 protocol (synchrophasor data) support at all
of the serial ports F, 2, 3, or 4. Additionally, Port 1 allows two sessions of the
C37.118 protocol, which is described in Appendix I: Synchrophasors.
Modbus RTU Protocol
The SEL-751 provides Modbus RTU support. Modbus is an optional protocol
described in Appendix E: Modbus RTU Communications.
DNP3 (Distributed Network Protocol)
The SEL-751 provides DNP3 protocol support if the option is selected. The
DNP3 protocol is described in Appendix D: DNP3 Communications.
DeviceNet Protocol
The SEL-751 provides DeviceNet support. DeviceNet is an optional protocol
described in Appendix H: DeviceNet Communications.
IEC 60870-5-103 Protocol
The SEL-751 provides IEC 60870-5-103 protocol support if the option is
selected. The protocol is available on Ports 2, 3, and 4. All ports operate using
the same map settings. The IEC 60870-5-103 protocol is described in
Appendix G: IEC 60870-5-103 Communications.
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