Pilot Communications SPM93 - Function Field; Data Field

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9.2.3.2 Function Field
The Function Field is 1-byte long and tells the addressed slave which function to
perform. The Modbus functions supported by the SPM93 are listed in below Figure.
Function
Meaning
Action
0x01
Read Relay Output
Status
Obtains ON/ OFF information of one or
more relay output in SPM93 (0/1)
0x03
Read Registers
Obtains the current value in one or more
holding registers of the DFPM93.
0x05
Relay control
Write 0xFF00 to close (ON) the relay
Write 0x0000 to open (OFF) the relay
0x10
Preset Registers
Places specific binary values into a series
of consecutive holding registers of the
SPM93
9.2.3.3 Data Field
The Data Field varies in length depending on whether the message is a request or a
response packet. This field typically contains information required by the Slave device
to perform the command specified in a request packet or data being passed back by
the Slave device in a response packet.
In general, registers are transmitted in the order of high-order byte first, low order