ProSoft Technology MVI56E-MCM/MCMXT - Manual (Page 166)

Reference MVI56E-MCM ♦ ControlLogix Platform
User Manual Modbus Communication Module
Page 166 of 199 ProSoft Technology, Inc.
June 18, 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
0B 05 00 AC FF 00 CRC
The forcing of a coil via Modbus function 5 is 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 is "hot".
6.8.7 Preset Single Register (Function Code 06)
Query
This Function Code allows you to modify the contents of a Modbus 4x range in
the Slave. This writes to a single register only. 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 Slave address zero (Broadcast mode) all Slave 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.
Note: This is the structure of the message being sent out to the Modbus network. The byte values
below are in hexadecimal display.
The example below is a request to write the value ‘3’ to register 40002 in slave
11.