Prosoft-technology MVI69E-MBS Instrukcja Użytkownika Pobierz pdf (Strona 120)

Reference MVI69E-MBS ♦ CompactLogix Platform

User Manual Communication Module

Page 120 of 162 ProSoft Technology, Inc.

January 6, 2014

Node

Address

Function

Code

Data Coil Point

High

Data Coil Point

Low

Data On/

Off

Data

Error Check

Field (2 bytes)

CRC

The forcing of a coil via Modbus function 5 happens regardless of whether the

addressed coil is disabled or not (In ProSoft products, the coil is only affected if

you implement the necessary ladder logic).

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".

7.2.7 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 load

the specified register with the contents specified.

Note Functions 5, 6, 15, and 16 are the only messages that are recognized as valid for broadcast.

The example below is a request to write the value ‘3’ to register 40002 in slave

11.

Node

Address

Function

Code

Data Start

Point High

Data Start

Point Low

Preset Data

High

Preset Data

Low

Error Check

Field (2 bytes)

CRC

1 2 ... 115 116 117 118 119 120 121 122 123 124 125 ... 161 162

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