Schweitzer Engineering Laboratories SEL-701, Instruction Manual

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Date Code 20010719
701 Motor Protection Relay
Modbus
®
RTU Communications Protocol
07h Read Exception Status Command
C.11
07h Read Exception Status Command
The SEL-701 Relay uses this function to allow a Modbus master to read the
present status of the relay and protected motor.
Table C.11 07h Read Exception Status Command
If the bit is set (1), the output contact is asserted or the motor is in the indicated
condition. If the bit is cleared (0), the output contact is deasserted or the motor is not in
the indicated condition. In the event that both Bits 6 and 7 are cleared, the motor is
starting.
Table C.11 07h Read Exception Status Command
Bytes Field
The Master Request Must Have the Following Format
1 byte Slave address
1 byte Function code (07h)
0 bytes No data fields are sent
2 bytes CRC-16 for message
A Successful SEL-701 Relay Response Will Have the Following Format
1 byte Slave address
1 byte Function code (07h)
1 byte Status byte
2 bytes CRC-16 for message
The Status Byte is Sent LSB-First, and Consists of the Following Bits
Bit 0 Trip Output Status
Bit 1 OUT1 Output Status
Bit 2 OUT2 Output Status
Bit 3 OUT3 Output Status
Bit 4 ALARM Output Status
Bit 5 0
Bit 6 Motor Stopped
Bit 7 Motor Running