ProSoft Technology PLX31-EIP-SIE - Manual (Page 144)

MBS Protocol PLX3x Series
User Manual Ethernet and Serial Gateways
Page 144 of 218 ProSoft Technology, Inc.
September 17, 2014
Response
The normal response to the Command Request is to re-transmit the message as
received after the coil state has been altered.
Adr Func Data Coil # Hi Data Coil # Lo Data On/ Off Data Error Check Field
11 05 00 AC FF 00 CRC
The forcing of a coil via MODBUS function 5 will be accomplished regardless of
whether the addressed coil is disabled or not (In ProSoft products, the coil is only
affected if the necessary ladder logic is implemented).
Note: The Modbus protocol does not include standard functions for testing or changing the
DISABLE state of discrete inputs or outputs. Where applicable, this may be accomplished via
device specific Program commands (In ProSoft products, this is only accomplished through ladder
logic programming).
Coils that are reprogrammed in the controller logic program are not automatically
cleared upon power up. Thus, if such a coil is set ON by function Code 5 and
(even months later), an output is connected to that coil, the output will be "hot".
Preset Single Register (Function Code 06)
Query
Function (06) allows the user to modify the contents of a holding register. Any
holding register that exists within the controller can have its contents changed by
this message. However, because the controller is actively scanning, it also can
alter the content of any holding register at any time. The values are provided in
binary up to the maximum capacity of the controller unused high order bits must
be set to zero. When used with server address zero (Broadcast mode) all server
controllers will load the specified register with the contents specified.
Note Functions 5, 6, 15, and 16 are the only messages that will be recognized as valid for
broadcast.
Adr Func Data Start Reg
Hi Data Start Reg
Lo Data #of Regs Hi Data #of Regs Lo Error Check Field
11 06 00 01 00 03 CRC