Micromod MOD: Modcell 2050R MODBUS Communications - Manual (Page 39)

IB-23C650M
MODBUS PROTOCOL
Table 2. MODBUS messages supported by the 2050R Controller
MODBUS
Function
Code
MODBUS
Message Name
2050R Definition
01 Read Coil
Status Read "n" consecutive discrete (boolean) points
from a specified starting point. The controller
returns zeros for points which do not contain
defined data and will nak any request for point
numbers greater than 9999. See Note, page 34.
02 Read Input
Status Same as Read Coil Status.
03 Read Holding
Registers Read "n" consecutive registers from specified
starting register. The controller returns zeros for
registers which do not contain defined data and
will nak any request for register numbers greater
than 9999. See Note, page 34.
04 Read Input
Registers Same as Read Holding Registers
05 Force Single
Coil Write one discrete (boolean) point. The controller
will nak this if the point is not currently writeable.
06 Preset Single
Register Write one register. The controller will nak this if
the register is not currently writeable. It will also
apply any currently applicable limits to the value
before storage in the database.
08 Loopback
Diagnostic Test Echo the message. Only "Return of Query" is
supported.
15 Force Multiple
Coils Write "n" consecutive coils from a specified
starting coil. The controller will nak if any of the
coils are not currently writeable, but will still do all
the writes which are valid. See Note, page 34.
16 Preset Multiple
Registers Write "n" consecutive registers from a specified
starting register. The controller will nak if any of
the registers are not currently writeable, but will
still do all the writes which are valid, applying any
currently applicable limits to the values before
storage in the database. See Note, page 34.
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