E.13
Date Code 20100129
Instruction Manual
SEL-751A Relay
Modbus RTU Communications
Communications Protocol
Coil addresses start at 0000 (i.e., Coil 1 is located at Coil address 0000). If the
device is disabled or the breaker jumper is not installed, it will respond with
error code 4 (Device Error). In addition to Error Code 4, the device responses
to errors in the query are shown in
06h Preset Single
Register Command
The SEL-751A uses this function to allow a Modbus master to write directly
to a database register. Refer to the Modbus Register Map in
for a
list of registers that can be written by using this function code. If you are
accustomed to 4X references with this function code, for six-digit addressing,
add 400001 to the standard database addresses.
, the command response is identical to the command required by
the master.
74
01, 05
Pulse RB16
75
01, 05
Pulse RB17
76
01, 05
Pulse RB18
77
01, 05
Pulse RB19
78
01, 05
Pulse RB20
79
01, 05
Pulse RB21
80
01, 05
Pulse RB22
81
01, 05
Pulse RB23
82
01, 05
Pulse RB24
83
01, 05
Pulse RB25
84
01, 05
Pulse RB26
85
01, 05
Pulse RB27
86
01, 05
Pulse RB28
87
01, 05
Pulse RB29
88
01, 05
Pulse RB30
89
01, 05
Pulse RB31
90
01, 05
Pulse RB32
a
Pulsing a Set remote bit will cause the remote bit to be cleared at the end of the pulse
(1 SEL
OGIC
Processing Interval).
Table E.15
Responses to 05h Force Single Coil Query Errors
Error
Error Code Returned
Communication Counter
Increments
Invalid bit (coil)
Illegal Data Address (02h)
Invalid Address
Invalid bit state requested
Illegal Data Value (03h)
Illegal Register
Format Error
Illegal Data Value (03h)
Bad Packet Format
Table E.14
01h, 05h SEL-751A Output
(Sheet 4 of 4)
Coil Address (Decimal)
Function Code Supported
Coil Description
Summary of Contents for 751A
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