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DEVICE
NOTE:
Function Code 03H (Read Setpoints)
4–24
MODBUS SLAVE ADDRESS
Range: 1 to 254 in steps of 1
Default: 254
For the RS485 ports each 869 must have a unique address from 1 to 254. Address 0 is
the broadcast address to which all Modbus slave devices listen. Addresses do not have
to be sequential, but no two devices can have the same address, otherwise conflicts
resulting in errors occur. Generally, each device added to the link uses the next higher
address starting at 1.
MODBUS TCP PORT NUMBER
Range: 1 to 65535 in steps of 1
Default: 502
The TCP port number used with Modbus over Ethernet. Note that the maximum number
of simultaneous Modbus connections supported over Ethernet is:
•
three for an 869 without the communications card,
•
five for an 869 with the communications card.
COMPATIBILITY
Range: Disabled, SR469
Default: Disabled
The Compatibility mode changes the Modbus actual value registers to emulate the
SR469. The emulation supports typical actual value data for common data items. See
the 8 Series Protective Relay Communications guide for the list.
When the device is programmed as a SR469, 869 actual values cannot be retrieved from
Modbus.
MODBUS ACTIVITY TIMEOUT
Range: 0 to 3600 s in steps of 1
Default: 0 s
The Modbus Activity Timeout specifies the minimum time without Modbus
communication. This timeout is used to declare the Modbus 'Loss of Communication'
state.
The Modbus state is always Active if the Modbus Activity Timeout is 0 s.
MODBUS ERROR RESPONSES
The following exception response codes are implemented.
Error ID
Exception
01
ILLEGAL FUNCTION
02
ILLEGAL DATA ADDRESS
03
ILLEGAL DATA VALUE
Modbus Implementation: Read Holding Registers
869 Implementation: Read Setpoints
For the 869 implementation of Modbus, the function code can be used to read any
setpoints ("holding registers"). Holding registers are 16 bit (two byte) values transmitted
high order byte first. As a result all 869 Setpoints are sent as two bytes. The maximum
number of registers that can be read in one transmission is 125.
Description
The function code transmitted is not one of the
functions supported by the 869.
The address referenced in the data field transmitted
by the master is not an allowable address for the 869.
The value referenced in the data field transmitted by
the master is not within range for the selected data
address.
869 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 4: SETPOINTS
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