Preset Multiple Registers (Function Code 16) - ProSoft Technology CompactLogix MVI69E-MBS User Manual

MVI69E-MBS ♦ CompactLogix™ Platform
Modbus Serial Enhanced Communication Module

8.2.12 Preset Multiple Registers (Function Code 16)

Query
This Function Code allows you to modify the contents of a Modbus 4x range in the slave.
This writes up to 125 registers at time. Since the controller is actively scanning, it also
can alter the content of any holding register at any time.
Note: Function codes 5, 6, 15, and 16 are the only messages that are recognized as valid for broadcast.
The example below is a request to write 2 registers starting at register 40002 in slave 11.
Note: This is the structure of the message being sent out to the Modbus network. The byte values below are
in hexadecimal display.
Func
Node
Code
Address
10
0B
Response
The normal response to a function 16 query is to echo the address, function code,
starting address and number of registers to be loaded.
Func
Node
Code
Address
10
0B
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Data Start Data Start Number
Address Address of Points
High Low High
00 01 00
Data Start Data Start Number
Address Address of Points
High Low High
00 01 00
Number Byte
Data
of Points Count
High
Low
02 04 00
Number Error Check Field (2 bytes)
of Points
Low
02 CRC
User Manual
Data Data Data Error
Low High Low Check
Field (2
bytes)
CRC
0A 01 02
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Reference