ProSoft Technology MVI69L-MBTCP - Manual (Page 119)

MVI69L-MBTCP ♦ CompactLogix Platform Reference
Communication Module User Manual
ProSoft Technology, Inc. Page 119 of 152
January 6, 2014
7.2.10 Preset Multiple Registers (Function Code 16)
Query
This Function Code allows the user to modify the contents of a Modbus 4x range
in the server. This will write 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 will be recognized as valid for
broadcast.
The example below is a request to write 2 registers starting at register 40002 in
server 11.
Node
Addrs Func
Code Data Start
Addrs
High
Data Start
Addrs
Low
Number
of
Points
High
Number
of
Points
Low
Byte
Count Data
High Data
Low Data
High Data
Low Error
Check
Field (2
bytes)
0B 10 00 01 00 02 04 00 0A 01 02 CRC
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.
Node
Address Function
Code Data Start
Address High Data Start
Address Low Number of
Points High Number of
Points Low Error Check
Field (2
bytes)
0B 10 00 01 00 02 CRC